You have two problems:
(1) You can't use migration assistant to move Creative Suite software from one computer to another.
You have to clean off the new computer, and use a new installer (or your old DVD/CDs) to install the CS applications:
(2) But the bigger problem is that CS5 and CS6 don't install or run well under Mac OS X 10.11. Even CS6 is four years old and is end-of-life. You'll be on your own since those applications are generally incompatible.
Don't believe Apple propaganda.
Any Adobe Software has to be installed from the original Adobe Installer (and other software supplier have the same requirement for their software).
Apple OS are also very bad when it comes to compatibility to older software or hardware. CS5 and CS6 will not work properly with El Capitan and you will loose also the compatibility to many scanners.
With El Capitan you will have to subscribe to Creative Cloud. A subscription includes CS6, CC, CC 2014 and CC 2015. CC 2016 will come in summer. CS6 from subscription is slightly different from the CS6 from the former package as it has got more updates and it uses also common software with later versions which has been adapted to EL Capitan. But it is slower on El Capitan than on older OS.
Interesting analogy. Most veterans of moving will tell you it's quite often better to throw away, give away or sell your old stuff rather than spend money to move it.
Having done that last year, I can tell you it's great advice.
Steve has already given you your choices so be prepared for headaches with old software on a new operating system.