Domain malfunction

<?php
//problematic line
require 'http://acadcalendar.42web.io/assets/vendor/autoload.php';
if (isset($_POST["submit"])) {
    $receiver = $_POST["receiver"];
    $subject = $_POST["subject"];
    $msg = $_POST["message"];

    $messagebird = new MessageBird\Client('******');
    $message = new MessageBird\Objects\Message;
    $message->originator = '*****';
    $message->recipients = [ $receiver ];
    $message->body = $msg;
    $response = $messagebird->messages->create($message);
    //var_dump($response);
    echo'<script type="text/javascript">';
    echo 'alert(\''.'SMS has been sent successfully!\n'.'\');';
    echo '</script>';
}
//irrelevant code