Your rewards should be awaiting you in the Royal Palace in Vizima. Check out the letter from Yennefer in your inventory if you need help locating them!
1. Make sure that you’ve linked your The Witcher 3: Wild Hunt with a GOG.COM account:
From the main menu of The Witcher 3: Wild Hunt open MY REWARDS and log in to your account.
2. Make sure that you are online and relaunch the game.