I don't know if the issue is with Ubuntu or if it's with Zorin but when I try to add my Facebook account with the GNOME Online Accounts menu, I get this error message:
Error getting identity: Could not parse response
I would like to ask about this on AU but I realise that it is Zorin OS and things aren't going to run exactly the same way as with Ubuntu. Their website does say, "Built on an Ubuntu Linux foundation, Zorin OS runs on the same Open Source software [as systems from the U.S. D.O.D to stuff on the I.S.S.]"
It is very obvious that it relies heavily on Ubuntu GNOME; it has the GNOME Control Panel, GNOME Extensions, GNOME Software, GNOME Indicators, and other features that are GNOME specific as well.