Open a AMD Rewards Support ticket and see what they recommend.
It is possible that maybe AMD may give out more codes to Micro Center.
Best to ask AMD Rewards Support that question.
Without the Game codes from Micro Center you can't open a AMD Rewards account to redeem the games.
NOTE: I have attached the two current 2020 AMD Promotions for you to download and read yourself if interested since you didn't post which AMD Product you purchased from Micro Center.