Adding apps to older Apple TV device

Which devices work with HBO Max? - HBO Max Help Center

Apple TV

Apple TV 4K (5th generation) or Apple TV HD (4th generation) with the latest tvOS software.

If you have an Apple TV (2nd or 3rd gen), see Other ways to stream on your TV (AirPlay).

only appletv hd(4g) and appletv 4k(5g) has storage to install apps on

earlier models rely on channels which are stored on apples servers