How can I connect my EA FC account from my pc to my Xbox?

Because I still have balance on my Xbox account, I am trying to get my FC ultimate team from my PC to my XBOX so that I can spend my money on packs on my main FC game, but I can't. I have already linked my XBOX account to my EA account but that doesn't work and now I don't know what to do.

Can someone please help me with my problem because I really don't like that I can't spend my money on something I want? Thanks a lot in advance!