It works the same as all Bungie Reward codes have - you are expected to claim the code by the code claim deadline. Ordering is then allowed for a few weeks afterwards (ordering deadline). You should have copied or written down the code when you used the link. Unfortunately, it is no longer accessible now.
English
-
I've claimed previous moments of triumph shirts on the day of the ordering deadline with zero issues redeeming a code. The wording of the deadline makes no indication that the code I already redeemed will disappear after that date especially when there is a period of time in between redeeming and ordering deadlines. There are a lot of other people who are running into the same problem.