This is how:
1. First, please visit the redeem website.
2. You will be prompted to log into the website with your Ubisoft Account, if you have not already done so. Please make sure you log in with the account you want to play the game with.
3. The website will ask you to validate your email address. Please double check that your email address is correct as you will receive an email to the address shown here later. You can change the email address on the redeem website, if necessary, and continue with the redemption afterwards. Alternatively, you can change your email address on the Ubisoft Account Management website.
4. On the next page, please select the platform on which you play Assassin's Creed: Odyssey and enter the code below.
5. Your code will be validated and the item will be granted to the Ubisoft Account you logged in with.
Some items might need to be claimed from Ubisoft Connect and the in-game Store > Owned before they become available to you in your Inventory in-game.