why have to pay for apple tv and then pay for conte

Just select the Apple TV+ tab in the sidebar and you will see the content you can view for free with your Apple TV+ subscription.

The Home tab includes other services that you would need to already have a subscription for. This is the same as Hulu, Paramount+, Prime, and others where you can watch a show on the platform when you also have a subscription to another streamer.

The Store tab has even more shows/movies that can be purchased or you can also rent those shows. The Store tab is available even if you do not have a subscription and some people still want to own movies/shows even when they do have a subscription.

apple have a apple produced material streaming subscription service called appletv+

this is what you can subscribe to

apart from that then they host and sell and rent out material from other content providers which are not a part of appletv+ and those are things you need to rent or purchase

you can read more about appletv+ here

Apple TV+ - Apple