Official supported support statement (applies unless otherwise stated on each plugin):
We support Xojo 2013r4.1 and later (up to date of the publishing of each plugin). Older versions will often work with our plugins but we do not support it officially or test for it in any way. (Some plugins may require newer version of Xojo) - Many plugins still ship with old style Real Studio version of the plugin also, those come as is untested, and will not be maintained in any way, if you want to be sure something works on old Real Studio then request old versions of the plugins from us from the times of Real Studio.
We support MacOS X 10.7 and later, Windows XP, Windows 2003 Server, Windows Vista, Windows 7 and Linux systems per the specs published by Xojo Inc. Plugins will often work for other systems outside of those specs, but we do not support it officially nor test for it in any way.