Adding Facebook listings is now a bit harder than it used to be due to the company exploiting their monopoly and shutting down all external event access.
To get around this we’ve created Faceloader, a tool that pretends to be you, logs in and grabs your data, and then syncs it to a local iCal file. You can then share this file with OneDrive, Dropbox or Google Drive desktop sync. Leave it running on your computer and it will do periodic updates.
Full instructions here:
A simple gui application to create ical files with events from Facebook pages. This is still a very early version, it may include bugs. Please report any issues you come across Facebook has all but made it impossible for community groups to sync their data outside the platform.
The single biggest known issue is this currently only works for the next 5 upcoming events. We’re working on it!