JFBConnect has a new installer with v5.1 and it will install all of the plugins and modules you need and should upgrade everything much easier than in the past.
It will also update the SCLogin module with the latest that is compatible with the new v5.1 release of JFBConnect and the last few releases of JLinked.
JLinked has also been updated to enhance compatiblity with the new v5.1 release and you should update that as well, but it's not critical. That, also, can just be installed using the Joomla installation manager and will automatically upgrade JLinked for you.
I hope that explains, but if you need anything else, let me know.
Thanks,
Alex