@MADrag0nAm I going grazy now? 🤣 If a search doesn't point to a solution or even a remote suggestion about the cause then it sadly doesn't help the TS, right?
And if you have the game from Steam, it get activated when you run the game. You can't use the key to manually redeem the game on myEA. Largely because you can't use the key for the Origin version. When you run the game from Steam it should just work, but sometimes it doesn't and you get this error. So, the link @MADrag0n provided sadly won't work. Only thing you can do for as far as I know is giving Steam support proof of purchase and ask for your money back or a new key.
I want to point out that I'm not trying to be rude or something 🙂 Just wanted to correct where needed to help the TS point in the right direction. Edit: then lets do some self-correction; as @MADrag0n pointed out, the myEA-part of this post is most likely wrong and what @MADrag0n could still be right 🙂