Mac OS contains a setting called Gate Keeper which can sometimes prevent an applications from launching.
To fix this, tell Gate Keeper to allow launching applications from "Anywhere" using the directions on the Apple web site.
Alternatively, right-click the app and choose 'Open' from the contextual menu. The warning dialog about the unidentified developer will now have an 'Open Anyway' button.
If you still have questions about this, please reach out to us at firstname.lastname@example.org