I had Xd already installed when I updated to Creator's edition, so I uninstalled it and then installed it again. Interestingly the percentage got to 45% and then stopped, but soon after it jumped to 99%, and then was finished.
That makes it seem like the install is handed off to Windows to finish. PowerShell.exe seems to be Microsoft's version of macOS Terminal, so it's not surprising that it might get called to do the finishing.
Does C:\Windows\System32\WindowsPowerShell\v1.0\PowerShell.exe exist on your machine? It seems strange that in your version Windows and System32 are different case (WINDOWS\system32 instead of Windows\System32) to the real path. Not sure if that matters though.