I returned to the game after a while and found out I need to steamlink my account.
I have my profile public and own the game, but the linking process say otherwise.
One of the games you own is called "Supreme Commander: Forged Alliance"? Owning a different SupCom game wouldn't matter.
Do you actually own SC:FA? If you are able to play SC:FA because of "family sharing" then you don't actually own it.
Those are the first two things that come to mind.
You need to set both your profile and your games list to public, make sure you did both
https://imgur.com/m008i0y make sure it looks like this you can reset it after the steam link!