A: Apple has restricted installation of software that is not Apple certified and due to your security settings that is why you are receiving the “ioGAS Installer is damaged..” error message. As a workaround please try the steps below:
1.   Choose System Preferences from the Apple Menu
2.   Click Security & Privacy
3.   If the preference is locked, click the Lock (lower left) and enter your admin password to unlock it
4.   In the General tab, set Allow applications downloaded from to Anywhere
5.   Click Allow From Anywhere
6.   Try running the installer again
7.   Optional: After installation, go back to the Security & Privacy preference and set it back to Mac App Store and Identified Developers