You need to copy auth.php to app/config (which is the auth driver config), and then change the driver listed to 'ormauth'. You also have to copy ormauth.php to app/config, and change it if needed.
Once you have done that, you can run the Auth migrations through OIl, which will detect you have configured Ormauth, and will create the required tables for it. The migrations will also create a default admin user (password = admin) with super-admin access.
Simpleauth is a different driver set (see the documentation), so you won't use both at the same time.
So, Mea maxima culpa, i had misunderstanding about the config, it's look fine now... And special bonus for the super_admin, i resume my build... Thank's a lot !