Help me with my Ark play anywhere?

So, my father got Ark on Steam and I on Xbox one. Now he wanted to download the Microsoft version from play anywhere so that we can play together. Unfortunately, this does not work with the download. Is that because my father already has the Steam version? If so, do we have to uninstall the Steam version?

Play anywhere only works if he buys it from the Microsoft Shop

I have the Xbox one version and it says that you can transfer it to your pc via play anywhere. We don't want to buy it twice.

You can only play it once per active account… That means only you or only your father, but NOT, you two together… To do this -> buy it again… It's not that expensive…

I've already given away accounts to get players to my server…