ASTRONEER

The multiplayer is unclear from the current menus in this game. There is no cross platform multiplayer and no option to search for players. You must have the other players already added to your Friends list to join them. To play together, the player hosting must load their desired save file from the single player menu and then the second player will be able to select the host from their in game friends list to join.

Make sure to be both on Xbox, WIN10 doesnt allow to join other players for somehow
i have unlocked it trying to join my laptop dummy profile but it didnt work, it kept giving a failed to connect msg, but once i booted my old xbox1 and tried it with my xbox series x it unlocked just fine