Add-ons • Re: need help understanding how to install from the Classic Add-ons Archive

What I do is right-click Install, choose Save as, and download the .xpi file. I then open it with an archive handler, open install.rdf and change the max version for Pale Moon to the current version (if the information is not there, I copy the information for it from a theme installer). I replace the revised install.rdf file and drag and drop the modified.xpi file onto the window with the add-ons list.