I appear to have found the solution. After taking control of the WindowsApp folder (so I could browse inside it). I simply deleted the Adobe XD folder (note: I did need to tell Windows to terminate [with in App Settings] the app; it was "in use" despite rebooting my system). Then I went and told Adobe CC to install it.
So, either it's a permissions issue that Microsoft may have imposed on "Windows App" programs to prevent malware (Windows Store still updates apps just fine). Or there's a process that Adobe XD keeps restarting so the install hangs due to "in use" error, but is obfiscated, and doesn't actually throw up the prompt you get when trying to delete something "in use".
Now, I did try Terminate before, but if there's a process that XD keeps starting back up...well...then the only solution is to delete the entire XD Folder before that process can be started again.
Hi All,
We're so sorry for all the trouble. Usually, this error gets resolved after terminating XD related process from the Task Manager/Activity monitor. Please close CoreSync and all Adobe related processes from the Task Manager/Activity Monitor and try re-installing. If that doesn't help try a clean install.
If you still face the issue, please get in touch with our support team using this link: https://helpx.adobe.com/in/contact.html so that we can investigate further and report it to the team.
Hope it helps.
Thanks,
Harshika