how do I mirror my Mac Pro with Apple TV to my Samsung smart tv? thanks

Airplay... assuming it is a newish (2018+?) Airplay2 compatible smart TV and the Mac Pro is running Mojave or newer.

For older or dumber TVs you will need a screen mirroring app or an Apple TV.

If it does not work out of the box, "there's an App for that".

Check the Android App Store for an App that claims Apple-TV compatibility, and install that.