https://www.nvidia.com/en-us/account/redeem/
You need to click login and login with you Nvidia credentials. You need an active Geforce Now Membership (the free one works)
Contents:
Adventurer's Experience x 10
Mora x 10,000
Fine Enhancement Ore x 5
Squirrel Fish x 3
Northern Apple Stew x 3
Redemption is valid through July 23 and is available to all GeForce NOW members.
Instructions from the site:
TO REDEEM THE REWARD, PLEASE FOLLOW THE INSTRUCTIONS BELOW:
Click REDEEM
Copy reward code shown
Navigate to this URL: https://genshin.hoyoverse.com/en/gift
Follow the instructions provided on the screen