Do you have a crash log? You can see them either by running Mac's Console and selecting Crash Reports, or you can look in your "~/Library/Logs/DiagnosticReportsdirectory for any files starting withPacketTunnelProvider.` I'd be interested in looking at the most recent version of one of those files (if present).
Can you also check the Settings in the Zit Desktop Edge app? You can access them via the gear icon on the bottom left of the app. They should look something like this:
