How do I get Apple TV app on my Samsung tv

Select models Samsung TV are supported; see the list:

List of Apple TV app-supported smart TVs (and third party streaming devices) - Apple

For these models, the Apple TV app may be pre-installed by Samsung, or else available from the Samsung TV Appstore.

Unsupported models smart TV may need to connect an external streaming device that has (or can have) the Apple TV app: That can be an Apple TV box, or a third party streaming device:

List of Apple TV app-supported (smart TVs and) third party streaming devices - Apple

Get the Apple TV app or Apple TV+ app on your smart TV or streaming device - Apple Support

How to watch Apple TV+, MLS Season Pass, and more - Apple Support