I'm not the best at troubleshooting these things, but maybe somebody else can help if you answer a few questions:
What version of ZC did you download? 2.5?
What operating system are you using on your computer? The game is known to have some issues with Windows 8.
Are you using the ZC Launcher program? Since they started working on version 2.5 I've found the game seems to run only when opened through the Launcher.
