Authentication Service Provider Interface not found

Hi, I’m trying to install Authentication Plugin on cakephp 3.9 app
I followed the steps in


I installed the plugin using composer and modified Application.php and AppController.php

But I getting the following error

Fatal error: Interface ‘Authentication\AuthenticationServiceProviderInterface’ not found in

I added the following lines at the begining of Application.php

use Authentication\AuthenticationService;
use Authentication\AuthenticationServiceProviderInterface;
use Authentication\Middleware\AuthenticationMiddleware;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;

My cakephp installation is up to date. What could be wrong?
Where should I check if the source file for AuthenticationServiceProviderInterface exists?

Thanks

I solved the issue, it was a silly mistake.
I had installed the plugin on the wrong folder

please can you tell me how you solved it?? Im facing the same problem