Do you mean that you do not see an option for Store or Library in the app?
There are unfortunately and confusingly different editions of the Apple TV app.
One does support the Store and Library (and in-app third party subscription channels),
the other is just for Apple Original subscription content, formerly Apple TV+, and MLS (where available), and FNB (during the season, and where available).
There used to be a subtle name difference for the app editions (with or without “+”), but it seems that may be gone now.
Which edition is supported by your device, depends on brand and sometimes model. It is not user-choice, but instead support for the expanded app edition is negotiated with the device manufacturers.
Users with unsupported TVs and/or not fully supported streaming devices, can consider one of the streaming devices that does have the ‘full’ Apple TV app. That can be an Apple TV box, Roku, Fire TV, PlayStation (4, 5), Xbox (One, One S, X, S), ‘Chromecast with Google TV’-dongle, or Nvidia Shield TV.
Watch on these smart TVs and third party streaming devices - Apple Support
Apple TV app user guide for smart TVs and third party streaming devices - Apple Support
Apple’s disclaimer: “Not all features and content are available in all countries or regions, or on all streaming devices.” [8]