I made a mistake with my code

So if you didn’t see my previous post, I fucked up. I thought that my Xbox One was able to run the closed technical test when the survey actually meant an Xbox Series S. I’m not a tech guy so I thought it was the same thing.

I do have a Steam account though, so is it at all possible for me to change my platform of choice from Xbox to Steam? Or did I just waste a Marathon code? Any help is appreciated