FF14 ARR Steam not working with expansion from shop?

Hey i just started playing ff14 about a month ago and decided to buy the expansion. Because of the fact that the physical copy was 15€ less then the steam version i went to gamestop to buy it. I looked at the cover of the game and it only stated "Need Final Fantasy XIV: A Realm Reborn to play" so i bought it. At home i wanted to go to register the game gone to squex.to/register and registerd the game there, but when i go to mogry-stadtion and want to register it there it says wrong code. After looking again at the back of the game i noticed that there is a note that is smaller written then the system requirements that it dont work with the steam version. Why is that? I mean you shouldnt care where i buy my games and if both versions are for the PC it should also work. I feel ripped off because i cant see a reason why this should not work. I payed for FF14 ARR AND for FF14 HW and im not able to play it. :mad::mad::mad:

Unfortunately as you've discovered Steam and non-Steam versions aren't compatible. We don't officially know why, but a common theory seems to be that it's because Valve/Steam want a cut of the sales by forcing people to buy the Steam version of the expansion (even though they are exactly the same).

Sadly there's nothing you can do but attempt to try and get a refund and then buy it on Steam.