Worked well for a while. With the Firefox 77 it fails in the private window. It can't reach or find their servers. The regular window still works. We'll see how much longer. Three tries to get help failed ending in: wait two days and try again, we'll email you, and finally: uninstall Firefox! None of the routine advice works: "allow in private window", logout/in, uninstall/reinstall.

This add-on works fine in normal mode, but will not work in Private Browsing.
I contacted the company and they told me that they are "working on it". The last update was nearly a year ago.
This does not indicate that they are actually working on it.

I have paid for a lifetime subscription to your service. I expect better than this.