Yes, Ubisoft Account linking works with Ubisoft+ memberships as long as you have added the game to your Ubisoft library. If you launch a Ubisosft game and see a message about entering your Activation or CD key, it means you have not added the game to your game library from the Ubisoft Connect app.
1. Download the Ubisoft Connect PC App, install, and login.
2. Select the Ubisoft+ tab and the game you would like.
3. Click the “Play” button.
4. You will receive a notification that the game has been added to your library. Return to the GeForce NOW app to launch the game.
You must also have an active Ubisoft+ membership to play. If your Ubisoft+ membership has expired, you will be unable to launch these games on GeForce NOW. You will also continue to see these Ubisoft+ games in your “My Library” and account linking will not automatically remove them.