use api

hello i need a basic help
im trying to use the api

`<?php

global $xoouserultra;

//get user url
$user_id = get_current_user_id();
echo ‘user id: ‘.$user_id; // return user id
$current_user = $xoouserultra->api->load_user($user_id,’id’);
?>
`

and im getting
Fatal error: Call to a member function load_user() on a non-object

https://ww.wp.xz.cn/plugins/users-ultra/