In order to interface with Photoshop Elements 11, you will need to use the Elements 11 Organizer. You can't interface with the Elements 12 Organizer.
You can probably find more information at the Photoshop Elements forum, by the way. This is the Premiere Elements forum.
I am strictly an Elements Windows user. SG has Elements Mac versions and he has responded to your question.
But, I would like to tell you of my observations related to what you are trying to do.
In my case, I have a desktop Windows 7 64 bit computer that refuses to open Photoshop Elements 12 to the Full Editor. No way. I also have Premiere Elements 12 Editor and Elements Organizer 12 that are working on this same computer.
So, this is what I tried. I accessed Elements Organizer 12 from the Organizer tab at the bottom of the Premiere Elements 12 Expert workspace.
In the Elements Organizer 12, I went to Edit Menu/Preferences/Editing and set the "Use a Supplementary Editing Application" for
C:\Program Files (x86)\Adobe\Elements Organizer\Photoshop Elements 11.0.exe. No problems in doing that.
After that, when I go back to Elements Organizer 12, select a photo, and use Editor Icon (bottom of Elements Organizer 12 workspace)/External Editor choice), the photo opens in Photoshop Elementd 11 Full Editor ready for editing.
I have not really explored the what next part of all this. But, if I save the photo edited in Photoshop Elements 11 to Pictures, I find that Elements Organizer 12 will pick it up under the Watched Folder feature.
I have no idea how much of any of that is applicable to Premiere Elements on a Mac computer operating system.