To install AP Manager on OSX 10.8 or 10.9 and above, you will need to disable Gatekeeper. Please follow the steps below:
1. Navigate to System Preferences from the Apple Menu or from the Dock.
2. Click on the Security & Privacy preference pane, under the Personal header.
3. In the Security & Privacy pane, click on the Lock icon on the bottom-left.
4. Enter your Mac's username and password and click Unlock.
5. Click the radio button next to Anywhere.
6. When prompted, click Allow From Anywhere. You can now install any compatible application on your Mac without the installation being blocked.
After updating any necessary software, follow the above instructions until step 5, and click the radio button next to Mac App Store and identified developers. Then close the System Preferences window.
Images and tutorial from the University of Chicago