I got a new MacBook Pro running Mac OS Sierra and tried to install Adobe Creative Suite CS5.5 on it, which I already had on my old MacBook Pro. I downloaded the package directly from the Adobe web page, but when I run Install.app from the disk image, I get an error message:
"Install.app" could not be opened. You must extract the disk image.
When I clicked the help button from this error message, I received the following explanation:
I searched the website and introduced suggestions to disable Gate Keeper functionality from the terminal so that I could install software from unknown developers, but that did not work for me.