If you pre-registered before the challenge launched, you likely already have your code waiting for you at redeem.nvidia.com. You’ll also receive an email once it’s ready.
If you didn’t pre-register, you’ll need to play through the GeForce NOW KovaaK’s Ultimate challenge at least once with a free or Priority membership. Simply open the GeForce NOW app on your PC or Mac and launch the GeForce NOW KovaaK’s Ultimate challenge. Then, stream the custom demo on your existing membership plan.
Make sure you are opted in to receive rewards. You can check your status here
You’ll be notified by email when your free 1-day upgrade to Ultimate is available.