I cant find the Apple TV app. My device is not compartible with Aple TV+ app. help

if you have a mac it needs to be macOS Catalina 10.15 to have the appletv app older macos can't use the appletv app

if you have an older mac or a windows machine you need to view appletv+ in a browser go to Apple TV+

if you are talking about on your tv then not all tvs support the appletv app read Apple TV app - Devices - Apple

if you want to know more

All the ways to watch Apple TV+ - Apple Support

Apple TV 4K, tvOS 11

If you are really on tvOS 11, you will need to update to get and use the TV app with Apple TV+.

tvOS 11 was current from 2017-09 to 2018-09.

tvOS 12.3 added the redesigned TV app, compatible with Apple TV app Channels, including Apple TV+.

tvOS 14.2 is the current version system software, per 2020-11-05.

How to update your Apple TV - Apple Support