I recently had a problem with my iTunes, saying it has insufficient permissions to start. I tried to see where could be possible I don't have enough permissions on my C: drive (I am an administrator using a Microsoft Account).
I do not have pictures to share, but believe me - it seemed odd. My UAC is off, and it seems like Windows ignored my configuration, asking me to continue as admin for every file-system related action.
I had the same problem with Windows 10. I have admin rights, checked all security rights; I right-clicked the shortcut icon for iTunes- on the bottom right was an Advanced button.
Click and it gives and option to Run as administrator; despite already being an administrator it worked.
The problem originates from not verifying your Microsoft account against your computer.
I accidentally encountered this, and it solved my problem.
I admit, this is a major issue, and I did not see any indication from Windows that I will have limited permissions for file-system and other admin related actions.
I am sorry I do not have pictures to guide you with.
To solve this:
Start --> type 'settings' --> Accounts --> There you should see a 'You need to verify your identity on this PC'.
There you need to complete your email address and insert the received code. This will verify your Microsoft account against the computer and restore 'admin' state/ privileges.
