Hey there.
Your Ubisoft account has been deleted or your Steam account? Just like your Steam account the game is bound to that specific account and cannot be linked to another account.
We can however double check to make sure you're launching the game from the correct account.
Are you aware of any other Ubisoft accounts you own? If so I would recommend signing in on those and trying to launch again. When you're on the correct account you will no longer see this error.
If you're not sure of any other accounts you have if you can send through a screenshot from the following folders to us on a support case please. Do not post those images here. By default they will be found at the paths below, you might have one or sometimes both of these folders:
C:\Program Files (x86)\Ubisoft\Ubisoft Game Launcher\cache\user_profile
C:\Program Files (x86)\Ubisoft\Ubisoft Game Launcher\cache\ownership
You can reach us either through the
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