Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Sorry to know that it is showing as invalid, you may go to https://rewards.bing.com/redeem/orderhistory and resend it again and if it still shows as invalid then you can reach out to the rewards team via https://go.microsoft.com/fwlink/p/?LinkID=823675 to report this issue that you have encountered.