Welcome to the Centrify Express forums.
RedHat 6.8 and its derivatives (e.g. CentOS) will be officially(*) supported with Server Suite 2017.
(*) This means that our QA has fully tested all our toolset.
However, several folks have been using our DirectControl client on this version without major issues that I'm aware.
Others inquired as well (here's the full setup sequence in CentOS 6.8 - same RPM for RHEL 6.8)
http://community.centrify.com/t5/Centrify-Express/Support-for-centos-6-8/m-p/24537
We encourage you to check out our commercial version for richer functionality.
R.P