Error: RegisterUserController could not be found

Hi
I bought the following application:

But its technical support is very poor or non-existent.

I hired an app programmer to set up and launch the app.
He installed the control panel and API module.
The problem is when registering in the application, it takes the token and the ID and registers them via the API, then the response comes to null.

Can anyone give advice?

See at folollwing error mesage.

CakePHP: the rapid development php framework

Missing Controller
Error: RegisterUserController could not be found.

Error: Create the class RegisterUserController below in file: app/Controller/RegisterUserController.php

<?php class RegisterUserController extends AppController { } Notice: If you want to customize this error message, create app/View/Errors/missing_controller.ctp Stack Trace APP/webroot/index.php line 110 → Dispatcher->dispatch(CakeRequest, CakeResponse) ROOT/index.php line 41 → require(string) CakePHP: the rapid development php framework CakePHP 2.8.4