samsung tv

The Apple TV App has been appearing on select Samsung TVs since May 13, 2019, as the first 3rd party brand to offer the app.

Samsung has something to say about signing in:

Sign into the Apple TV app - About the Apple TV app on your Samsung TV - Samsung Support

but Apple’s support page is probably more informative and complete:

Set up the Apple TV app on your smart TV - Apple Support

For the signup to work, the TV needs a reliable internet connection to Apple servers. No firewall blocked ports that may be needed. No VPN or alternative DNS on the router that may interfere by incomplete DNS resolving. Correct time and time zone setup to facilitate secure connections.

ReeBee123 wrote:

I don't have an Apple TV. I'm trying to sign-in to the Apple TV app on my Samsung tv.

At the moment, you need an TV.

The Apple TV app is here. And soon, everywhere. The new Apple TV app is already on iPhone, iPad, Apple TV 4K, and Apple TV HD. And this fall, we’re bringing the Apple TV experience to Mac. It’s also coming to popular smart TVs, streaming boxes, and streaming sticks, starting with Samsung.

See here: TV - Apple

No idea.

Which TV model do you have?

Not asking about Samsung TV.

Which Apple TV model do you have?

Where sign in are you talking about?

Apple says:

It’s also coming to popular smart TVs, streaming boxes, and streaming sticks, starting with Samsung.

It not there yet, see my previous post.