How to convert CC files to something CS6 can open?

Bob,

Inevitably, there are and will be (more, as CC grows further (apart from CS6)) things that you can do in newer versions and which have no (true) counterparts in older versions, so the real solution is to have whomever created the document(s) downsave.

cc files can be opened by cs6 versions.  a warning will appear, but that doesn't prevent opening.