can't stream some services on my 3rd gen apple tv

The third gen Apple TV received pre-chosen apps instead of utilizing an App Store. If you do not see the desired app in the menu settings, then you will need to upgrade to a gen 4 or higher. In addition there have been a few apps that have discontinued support for the third gen TV recently. It’s possible the app you are looking for was one of those as well.

The 3rd gen uses preset channels, which are sent via server. Many providers have started to drop support for those, Youtube was the latest. Best to clarify if the services in question are in fact still supported.