Parallels can not access Desktop/Documents etc. on Mac

This morning Parallels wanted to update Parallels Tools. This failed initially, and the programme forced me to do it again.
After the VM restarted Parallels could no longer access Desktop/Documents etc. on my Mac, essentially rendering the VM unusable.
I have spent the last 4 hours trying to reinstall Parallels Tools without any luck.
I followed every step in this article:
https://kb.parallels.com/8969
I'm not stuck in the advanced troubleshooting step after command centre gave me an 'access denied' message after typing in the long command prompt (I am logged in as administrator).
I really don't know how to proceed from here.