Windows won't activate after creating new user and reinstalling windows

I am running Parrallels Desktop 15 for Mac on a MacPro running MacOs Mojave. I needed to change the users on it so I changed the current users home directories and ids to the new users (followed all the suggested protocols to do so) leaving no sign of the old user. But when I logged in as the new user all worked fine, but Windows wanted/needed to be reinstalled... which was a pain, but was not a hill to die on.... But the new windows installation is coming up as not registered and when we try to input the previously used (on the same machine, in the previous user) product code won't work. Any body know why?