The basic profile information is not being displayed using Instagram API

I am trying to create a login with instagram form. However at the callback.php, there is no information displayed.

Kindly let me know what could be the possible issue.

Callback.php:

<?php
    session_start();

    if (isset($_GET['error'])) {
        header('Location: login.php');
        exit();
    }

    require "InstagramAPI.php";

    $data = $Instagram->getAccessTokenAndUserDetails($_GET['code']);

    $_SESSION['loggedIn'] = 1;
    $_SESSION['accessToken'] = $data['access_token'];
    $_SESSION['id'] = $data['user']['id'];
    $_SESSION['username'] = $data['user']['username'];
    $_SESSION['bio'] = $data['user']['bio'];
    $_SESSION['website'] = $data['user']['website'];
    $_SESSION['fullName'] = $data['user']['full_name'];
    $_SESSION['profilePicture'] = $data['user']['profile_picture'];

    header('Location: index.php');
    exit();
?>