1) Install Sync
2) Enter Server Credentials, select Site Settings
3) Click OK
4) Reboot Computer (this also shuts down the locally running server so the server is no longer available).
5) Sync starts up.
6) Open Sync Properties.
7) Uncheck Start Liferay Sync On Login.
You are unable to click OK because the server is not up and running.
This is an awkward constraint.