Dorico 4 keeps trying to Autosave to wrong location

Presumably you copied the user folder from one computer to the other, in order to transfer keyboard shortcuts, preferences etc.

Go into that folder (~/Library/Application Support/Steinberg/Dorico 4/ on mac or %appdata%\Steinberg\Dorico 4 on Windows), open preferences.xml, scroll to line 156 and replace the Autosave path with the correct user account name.