Quote Originally Posted by worldofneil View Post
Yes if you bought the game on Steam, you must buy all expansions on Steam, this was the same with Heavensward and does actually say this on the store page when purchasing Stormblood. Hope you can get it refunded okay!
Yeah, the SE Store page does specifically say it right underneath the spot where you choose your platform/version and is highlighted in red:

"Notice: This product is not compatible with the Steam version of FINAL FANTASY XIV: A Realm Reborn. If you’ve purchased FFXIV: A Realm Reborn on Steam, then you must also purchase FFXIV: Stormblood on Steam to upgrade your existing account."