ClockMaker will work on the following Operating Systems :-
Minimum of OS X 10.8 & higher is needed. It is code-signed for GateKeeper.
Snow Leopard users (10.6) should consider the free upgrade to 10.9 or higher.
Windows 8 & 8.1
Windows Server 2008 & Higher.
Please note that Windows XP and Vista are no longer supported. If it works, any future upgrades may not.