Unable to Install Application on OS X / Mac (Double-Clicking does Nothing)
Depending upon your settings, when using a Mac running OS X, you may be unable to install software that you didn't obtain from the App Store. Ostensibly this is a security precaution but does act to restrict installation of legitimate applications by major software developers.
Most software developers will be approved by Apple and therefore if you find you cannot install their application, your 'Security & Privacy' settings may be set to only allow software from the App Store to be installed. This is a standard setting on a new Mac.
Double clicking on a downloaded installer does nothing.
No issues installing from the App Store.
Warning/message preventing a software installer from running.
Go to your System Preferences (Apple Menu), select 'Security & Privacy' and click the padlock and authenticate if you need to change the allowed apps. You may also see the application you are having issues with listed here for approval.