For example, a player on Stadia can continue playing their missions with the same character if they move to playing on PC.
To take advantage of the feature, you need to link your Stadia account to your Ubisoft account.
Please note that although you do not need to own the game on both platforms for cross-play, it is necessary for cross-progression.
For example, if you do not own the Warlords of New York Expansion on PC and access the Expansion content on Stadia, your character will become inaccessible on PC.
Let us know if you have any other questions.