Hey, did you solve the problem?
I am having the same issue trying to redeem a Doom code. I have been redirected to https://www.amdrewards.com/amdrewards/ by the shop I bought the card from.
I started making an account and received both the e-mail and the SMS code. The problem is that inside the e-mail there is no confirmation code, just like you had, ctmone.
En exatract from the e-mail from AMD:
Thank you for registering to AMD Radeon™ Rewards! In order to continue, please click on the link below and enter the activation code upon request.
Cod de activare: %