[Koha] Koha not authorized to use CAS

Hello all, I am newbie for CAS and I'm trying to integrate some application with it (KOHA library). My CAS is running fine but when I'm trying to login to application with my CAS user I get the error "The application you attempted to authenticate is not authorized by CAS". I found out that I need to get the CAS server's Manager to add the OPAC Url to the Service Management system in CAS itself. But when I'm trying to acces it (https://localhost:8443/cas/services) it redirects me to the CAS login page. Does that means that I don't have CAS Service Management istalled or something else? I really don't know what to do so please, any help is appreciated. Thanks ! Ahmed