the vpn feature does not work

Did you turn it on? What makes you think that it does not work?

I successfully login and click on the start VPN and nothing happens. I turned of the Malware extension, and the pi-hole monitoring service.

I had the same problem, the software appeared to be stuck in a loop even after logging in.

The solution came by closing all instances of Firefox and reinstalling over the top of the existing installation.

Problem solved.