Thanks for the reply ,
What version of Windows 10 are you using?
Can you try this alternative to see if it's work :
Log in the administrator account
Type "Computer Management" in the search bar
Then go in.
Go to "Local user and groups" tab.
Right click on John name then click on "Properties".
Go to the "Profil" Tab
In the "Home folder" section ,
Click on "Connect"
Select "Z": as the letter then paste the path you want as home folder for John then apply .
Log off the administrator account and log in the John's account to see if everything is correct.