stream home movies from Mac with Catalina to 3rd generation Apple TV

I have a third generation Apple TV. I am trying to stream home movies from a MacBook with Apple TV (the app). I copied the home movie into Apple TV. When I click on the "computers" icon I get an error that it can not find my library. If I us an old MacBook running Lion, it works fine. The manual for the Apple TV says to turn on home sharing in iTunes which is gone from Catalina. I would appreciate it if anyone has an idea. Thanks very much!