Adobe CS apps cannot open files saved natively from Adobe CC apps.

The following Adobe CC apps support exporting to CS6 format: Photoshop, InDesign, Illustrator, Flash Professional, and Dreamweaver. What’s important to note is that these CC apps can only export down to CS6, not CS5 or older. This piece of information is critical if you plan on mixing Adobe CS apps and CC membership.

For more information, see http://prodesigntools.com/save-open-adobe-cs6-files-cs5-cs4-cs3.html