Yes, Ubisoft Account linking on GeForce NOW works with Ubisoft+ memberships. Simply complete account linking and refresh your connection from the GeForce NOW settings and supported Ubisoft+ games will be added to your "My Library" on future launches on GeForce NOW.
Note: You must have an active Ubisoft+ membership to play. If your Ubisoft+ membership has expired, you will be unable to launch these games on GeForce NOW.