Route problem

hi , this is a row of my Route:

$routes->add('admin/', 'Admin::index');

why  if i open this link :
http://localhost:8080/admin/
have i a 404 ?

https://imgur.com/OYFNzJ5.png

none of my routes have that trailing forward slash 'admin/' unless :

Code:

$routes->get('productCat/(:segment)','Product::getCategory/$1');

it i guess could also be that if index method of Class Admin calls a view which doesn't exist ?

CMS CI4     I use Arch Linux by the way