Bought Xbox game pass Ultimate yesterday but cannot download any games (PC)

If you have bought Game Pass Ultimate, then it includes Games Pass for Xbox, Game Pass for PC, EA Play for Xbox, Cloud Gaming on android & Xbox Live Gold. So yes, you can use it on your PC.

It's simple to use, download the Xbox app on your PC, log in with the account that has Game Pass Ultimate, and then download a game from the app, once downloaded, start the game.

They are playing on PC as well and with Game Pass Ultimate. I have Game Pass Ultimate and the game downloaded but cannot play with them because I did not download through the Microsoft Store?

They are playing on PC as well and with Game Pass Ultimate. I have Game Pass Ultimate and the game downloaded but cannot play with them because I did not download through the Microsoft Store?

As far as I am aware, there is no cross platform play between Steam and Xbox when it comes to Ark, so your Steam version cannot communicate with their Game Pass version of the game. You would have to download the Game Pass version of the game and start fresh
there in order to play with other people using the Game Pass version.

It depends on what you bought. There's Game Pass for Console, Game Pass for PC, and Game Pass Ultimate.

If you only bought Game Pass for console, then it won't work on a PC.

Game Pass Ultimate includes both version of Game Pass plus a Gold subscription. So if you bought Game Pass Ultimate, you should have access in both places.

Game Pass Ultimate benefits can only be shared on consoles. You cannot gain any benefits or use on PC unless you are signed into the account that purchased Game Pass Ultimate.