Uninstall FF after saving bookmarks/passwords/profile and delete all left overs in C:\ in all FOLDER NAMES Clean your computer cache/temp files and then try install with the full installer https://www.mozilla.org/en-US/firefox/all/

Please let us know if this solved your issue or if need further assistance.

I had already uninstalled FF. FF is not on may computer. Reinstalling per your instructions still does not work.

I am not that familiar with Mac OS but I do know some on older systems are moving to the Extended Release version https://www.mozilla.org/en-US/firefox/organizations/all/

Please let us know if this solved your issue or if need further assistance.