Try installing it to your system C drive. Sometimes you will need to close Ubisoft Connect completely (not just minimise it to the system tray) and then launch the game from Steam, for accounts to link correctly. @KETAMINE FIEND and @ Mop3yLion are you launching the game on a standard Windows PC or a different device?
https://steamcommunity.com/app/304390/discussions/1/828205158992231390/

