OK, well I couldn't get any of it to work. All the plugins seemed to be installed correctly in the proper subfolders, etc.
So, I uninstalled SU 7.1 Pro. Moved the contents of the Plugins folder to a temp folder, including all the zip files that were there. Reinstalled SU 7 Pro. Did the update to 7.1. Moved the zip files back to the plugins folder. Extracted LibFredo6 3.4c first, then the other Fredo6 plugins that I wanted/needed. It all works just fine now. Dunno what happened. "Take it from the top" seems to be the trick.