The game is FULL Cross-Play, Steem, Win10 (and Win11 i think), Xbox One, Xbox Series X|S.
She can play with you. You need to be her friend on Xbox (Xbox app on PC).
Either of you will have to start the game as a Multiplayer > Host Online Game. The other one of you will have to join a multiplayer game.
Note that ALL Save files can switch between MP and SIngle player.