Why can't I download a Twitch on my samsung tablet?

That just doesn't exist in the Playstore

Then download it from the internet

Do you mean the Twitch what the Playstore shows me as in the picture on my tablet?

https://apkpure.com/de/twitch-livestream-multiplayer-games-esports/tv.twitch.android.app

https://twitch-app.de.uptodown.com/android