PSE 9 - Mac w/o CD port - "install is damaged"

Hello,

I have tried to follow all guidelines on how to install PSE 9 onto my Mac OS X El Capitan - version 10.11.2. My family has had this photoshop package for a long time, the way it is supposed to be installed is by inserting a disc into your computer…. however my computer does not have a CD port. I have downloaded the installer package from the adobe website. The “Photoshop Elements 9” folder pops up on my screen after I downloaded, and is located in Finder. At this point I have read the “read me” file and still I don't know how to install this program onto my computer. It has not prompted me to enter a serial number (nor can I figure out where to put that in)… I do have a serial number for my product and an Adobe account.

When I open the photoshop folder, and I click on the “install” folder (red - application) it says “”install” is damaged and cant be opened. you should eject the disk image”. I tried to 'eject disk image' but it appeared to just do the same thing as when i chose “cancel”…. which was nothing. and when i tried to open it again it says the same thing.

I’m not sure what the next step is to download…

please help.

Thanks,

Freyja