First off, I apologize for the lengthy delay. We had an issue that was preventing us from responding to support requests but it is rectified now.
I hope you've been able to update to Joomla 4 along with JFBConnect. If not, please let us know the current problem you're experiencing and (believe it or not) we'll gladly help however we can and get you a response as soon as we can.
In general, JFBConnect v9 was built to support both Joomla 3 and Joomla 4 in the same package, so you should be able to install JFBConnect v9 on a Joomla 3 or 4 site before or after you upgrade without issue.
Thanks,
Alex