LoginApp/src/Controller/MainController.php

<?php

namespace App\Controller;

use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;

class MainController extends AbstractController
{
    /**
     * @Route("/loginAppSaml", name="login_app_saml")
     */
    public function loginAppSaml(Request $request)
    {
        return new Response('saml');
    }
}