How to activate free code during payment process Faceplate Ring Doorbell

After buying the Video Doorbell 4 i received a free faceplate code by email. During payment process of the black frontplate i tried to enter the code but could not find any "enter code" here. So at the end i bought the frontplate for the full amount of money and still didn't used the free code. I hoped there will be a tab at the end to enter the code before "payment completed". Is there a possibility Ring will pay me back and block the code i received? Now i payed 20 euro. Kind Regards, M11