Ah you didn’t mention which of the rewards.
For players already on a 12-month recurring subscription, you will receive the Astral Aurochs Skyriding mount, Grandiose Grrloc ground mount and Sha-scarred Drake flying mount as a gift in the Battle.net desktop app at no additional charge—provided that you have a future renewal date at the time the bonuses are delivered, no later than 31 October 2025 (must be redeemed by 30 April 2026).
Check back after 31 October if you haven’t received it in a giftwrap at your BNET client or ingame mount/pet journal please.