Get user access token using Facebook SDK for PHP

get_user_access_token.php

<?php

require_once __DIR__ . '/vendor/autoload.php';

session_start();

$fbData = array(
    'app_id' => '{APP ID}',
    'app_secret' => '{APP SECRET}',
    'profile_id' => '{PAGE ID}',
    'default_graph_version' => 'v2.5',
);
 
$fb = new Facebook\Facebook($fbData);
 
$params = array('req_perms' => 'manage_pages, publish_pages, public_profile');
$helper = $fb->getRedirectLoginHelper();
$loginUrl = $helper->getLoginUrl('http://fbsamples.local/callback.php', $params);
 
header('Location: '. $loginUrl);
exit;