I had donated years ago with a different email address and just donated again via PayPal for the Pro version.

Apparently the Firefox extension no longer works for the Pro version, instead a desktop app is downloaded. The new app is a beta and so far works. It has an input for a Registration Code as it is a beta, none is required. I did not receive a Registration Code so will this be provided at some point?

Also, I was unable to message the developer via the Contact message page as the Captcha verification doesn't work