Is After Effect CC and Premiere Pro CS6 compatible?

Yes.  To use Direct Link, the versions must match.  So you either have to download AE CS6 -- which you can do one you're renting -- or you can get later, matching versions of both.  You have access to everything from CS6 to CC 2016.

I'm partial to CC 2014 Applications -- for AE, anyway.  It still used multiprocessing, and CC 2014 had the least number of problems.

Later versions have a LOT more bugs in them, and actually broke features that previously worked just fine.  They were -- and still are -- screwy bugs that don't affect everyone.  Whenever you try to use the latest version of Adobe software any more, you automatically become part of the the Adobe Unpaid Beta Tester Program, whether you want to or not.