Routes file

CustomController.php

<?php

namespace App\Http\Controllers\Admin;

use Terranet\Administrator\ControllerAbstract;

class CustomController extends ControllerAbstract
{
    public function index()
    {
        dd('123');
    }
}

web.php

<?php

/**
 * Other routes
 */


Route::group(['prefix' => 'admin'], function () {
    Route::resource('custom', 'Admin\CustomController');
});