Error logging in to redeem codes.

Every time I redeemed the codes, one day I got a login error, saying I couldn't because I didn't have a FC account, and I simply didn't understand, because I was already logged in, both with Play Games and an FC account, and since then I haven't been able to redeem any codes. So I ask that you resolve my problem.

Thank you for your attention.

Sincerely, FC Mobile User.