Fatal error “Uncaught ArgumentCountError” with custom built plugin

I’m trying to make a plugin so that you can show events that have been made on a different site in your own WordPress site and I’m getting a fatal error and don’t know how to go further now.

Fatal error: Uncaught ArgumentCountError: Too few arguments to function Spond::__construct(), 0 passed in C:\wamp64\www\stage\wordpress wpm\wp-content\plugins\spond-plugin\spond-plugin.php on line 122 and exactly 2 expected in C:\wamp64\www\stage\wordpress wpm\wp-content\plugins\spond-plugin\s

This is my code:

<?php

/*
Plugin Name: Spond Event
Description: Display Spond events on your WordPress site.
Version: 1.0
Author: Merel Rose de Vries
*/
// spond-plugin.php

session_start();

include_once(plugin_dir_path(__FILE__) . 'spond-class.php');

function spond_shortcode($atts) {
    // Check if the form is submitted
    if ($_SERVER['REQUEST_METHOD'] === 'POST') {
        if (isset($_POST['logout']) && $_POST['logout'] == 1) {
            // Logout action: unset the session variable
            unset($_SESSION['spond_logged_in']);
            return 'Logged out successfully.';
        }

        $username = isset($_POST['username']) ? sanitize_text_field($_POST['username']) : '';
        $password = isset($_POST['password']) ? sanitize_text_field($_POST['password']) : '';

        // Assuming the form is submitted, redirect with form data as query parameters
        wp_redirect(add_query_arg(array('username' => $username, 'password' => $password), get_permalink()));
        exit();
    }

    // If there are query parameters, attempt to log in
    if (isset($_GET['username']) && isset($_GET['password'])) {
        $username = sanitize_text_field($_GET['username']);
        $password = sanitize_text_field($_GET['password']);

        // Your Spond class instantiation
        $spond = new Spond($username, $password);
        $spond->login();

        // Set a session variable to indicate the user is logged in
        $_SESSION['spond_logged_in'] = true;

        // Get and display events
        ob_start();
        $spond->get_events('74ED14831B694B679A0CB778A33D860F');
        return ob_get_clean();
    }

    // Check if the user has already logged in
    if (isset($_SESSION['spond_logged_in']) && $_SESSION['spond_logged_in']) {
        // User has already logged in, keep the session active
        return display_events();
    }

    // User is not logged in, display the login form
    ob_start();
    your_plugin_page();
    return ob_get_clean();
}
// Register the shortcode
add_shortcode('spond_events', 'spond_shortcode');
// Add menu item
add_action('admin_menu', 'spondplugin');

function spondplugin() {
    add_menu_page(
        'Spond-plugin',
        'Spond-plugin',
        'manage_options',
        'your_plugin_menu',
        'your_plugin_page'
    );
    add_submenu_page(
        'your_plugin_menu',
        'Submenu Page',
        'Submenu Page',
        'manage_options',
        'your-submenu-page',
        'your_submenu_page'
    );
}

// Create plugin page content
function your_plugin_page() {
    echo '<div class="wrap">';
    echo '<h1>Spond Evenementen</h1>';
    echo '</div>';

    // Check if the user is logged in
    if (isset($_SESSION['spond_logged_in']) && $_SESSION['spond_logged_in']) {
        // Display logout button
        echo '<form action="" method="post">';
        echo '<input type="hidden" name="logout" value="1">';
        echo '<button type="submit">Logout</button>';
        echo '</form>';

        // Display events
        display_events();
    } else {
        // Display the login form
        echo '<form action="" method="post">';
        echo '<div>';
        echo '<div class="container">';
        echo '<label for="username"><b>Username</b></label>';
        echo '<input type="text" placeholder="Enter Username" name="username" required>';

        echo '<label for="password"><b>Password</b></label>';
        echo '<input type="password" placeholder="Enter Password" name="password" required>';

        echo '<button type="submit">fetch</button>';
        echo '</div>';
        echo '</form>';
    }
}

// ...

// Display events function
function display_events() {
    ob_start();
    $spond = new Spond(); // Instantiate with default username and password
    $spond->get_events('74ED14831B694B679A0CB778A33D860F');
    echo ob_get_clean();
}
?>

<?php
// spond-class.php

echo '<style>';
include "style.css";
echo '</style>';

require_once plugin_dir_path(__FILE__) . 'vendor/autoload.php';

class Spond {
    private $username;
    private $password;
    private $api_url = "https://api.spond.com/core/v1/";
    private $token;
    private $groups;
    private $clientsession;
    private $accessToken;
    private $auth;
    private $auth_headers;

    public function __construct($username, $password) {
        $this->username = $username;
        $this->password = $password;
        $this->clientsession = new \GuzzleHttp\Client([
            'verify' => false,
        ]);
    }

    public function authHeaders() {
        return [
            "content-type" => "application/json",
            "Authorization" => "Bearer " . $this->accessToken,
            "auth" => $this->auth,
        ];
    }

    public function login() {
        $login_url = $this->api_url . "login";
        $data = ["email" => $this->username, "password" => $this->password];
        $options = [
            'http' => [
                'header' => "Content-type: application/json",
                'method' => 'POST',
                'content' => json_encode($data),
            ],
        ];
        $context = stream_context_create($options);
        $response = file_get_contents($login_url, false, $context);

        $login_result = json_decode($response, true);
        $this->accessToken = $login_result["loginToken"]; // Assuming loginToken is the access token

        return $this;
    }

    public function getGroups() {
        if (!$this->token) {
            $this->login();
        }
        $url = $this->api_url . "groups/";
        $response = $this->clientsession->get($url, ["headers" => $this->authHeaders()]);
        $this->groups = json_decode($response->getBody(), true);
        return $this->groups;
    }

    public function getGroup($uid) {
        if (!$this->token) {
            $this->login();
        }
        if (!$this->groups) {
            $this->getGroups();
        }
        foreach ($this->groups as $group) {
            if ($group["id"] == $uid) {
                return $group;
            }
        }
        throw new Exception("IndexError");
    }

    private function flattenArray($array) {
        $result="";
        foreach ($array as $key => $value) {
            if (is_array($value)) {
                //Flatten nested arrays
                $result .= $this->flattenArray($value);
            } else {
                $result .= "$key: $value, ";
            }
        }
        return rtrim($result, ', ');
    }

    public function get_events($group_id) {
        if (!$this->token) {
            $this->login();
        }

        $url = $this->api_url . "sponds/?max=100&groupId=" . $group_id;

        $headers = $this->auth_headers;

        $response = $this->clientsession->get($url, ["headers" => $this->authHeaders()]);

        $events = json_decode($response->getBody(), true);

        // Check if events array is not empty
        if (!empty($events)) {
            echo "<table><th>Evenementen</th>";

            foreach ($events as $event) {
                echo "<tr>";
                echo "<td>" . (isset($event['heading']) ? $event['heading'] : 'N/A') . "</td>";

                // convert to date
                $startTimestamp = isset($event['startTimestamp']) ? $event['startTimestamp'] : 'N/A';
                $startTimestamp = $this->date($startTimestamp);
                echo "<td>$startTimestamp</td>";

                // Convert to hour & minutes
                $startTimestamp = isset($event['startTimestamp']) ? $event['startTimestamp'] : 'N/A';
                $startTimestamp = $this->convertTimestamp2($startTimestamp);
                echo "<td>$startTimestamp</td>";

                // Convert to hour & minutes
                $endTimestamp = isset($event['endTimestamp']) ? $event['endTimestamp'] : 'N/A';
                $endTimestamp = $this->convertTimestamp2($endTimestamp);
                echo "<td>$endTimestamp</td>";

                echo "</tr>";
            }
            echo "</table>";
        }
    }

    private function date($timestamp) {
        $dateTime = new DateTime($timestamp);
        return $dateTime->format('Y-m-d');
    }
    private function convertTimestamp2($timestamp) {
        $dateTime = new DateTime($timestamp);
        return $dateTime->format('H:i');
    }
}
?>