Codeigniter restclient not working

I am trying to install the CodeIgniter RESTClient and RESTServer libraries for my solution. (philsturgeon-codeigniter-restclient and chriskacerguis-codeigniter-restserver ).

I managed to get the rest server up and running, but I am encountering issues with the rest client.

These are the steps I did to come where I am now:

1. Copy the Rest.php file (downloaded from GitHub) and put it in the libraries folder
2. Download the Curl library and put it in libraries
3. Modified the code in Rest.php to uncomment $this->_ci->load->library('curl'); (if I hover over the usages of the curl library in this file I get the following message):

Field 'curl' not found in CI_Controller

4. I create a new controller called "Restclient" to test my API. In this controller I created the following method:

   function rest_client_example($id)
   {
       $this->load->library('rest', array(
           'server' => 'localhost/codeigniter/api/users/'
       ));
   
       $user = $this->rest->get('volunteer', array('id' => $id), 'json');
   
       var_dump($user);
   }
   

Browsing to http://localhost/codeigniter/api/restclient/rest_client_example/25 then gives me

D:\wamp\www\codeigniter\application\controllers\api\Restclient.php:36:null

When executing the following code instead of the above, I do get a correct result:

    $this->load->library('curl');

    $t = $this->curl->simple_get('api/users/volunteer', array('id'=>$id));
    var_dump($t);

So I do know that the curl is working.

My guess is that I am doing something wrong with the loading of the curl library?