Hi. So the key you gave was for season pass. It was intentional ?
I have to ask the stuff what to di with this situation.
If i mark as received i will have unclaimed position.

edit:
After some digging i see that this dlc is not a part of season pass.
Worst case scenario is i will leave this not marked at all, to not harm your stats.
The best would be, you asking stuff to delete this giveaway.