Our software now only supports the latest stable version of Joomla! available. At the time of this writing it is 3.4.4. Using older versions is NOT recommended for security reasons.
This version requires PHP 5.3.4 or later (e.g. 5.3.29 which is twenty five versions newer than PHP 5.3.4), 5.4, 5.5 or 5.6. Please note that PHP 5.3 is obsolete since August 2014 and we're going to stop supporting it without warning in future versions of our software. We'd like to remind you that Joomla! 3.x does not currently support PHP 7. Since our software runs inside Joomla! by definition our software doesn't currently run on PHP 7 either.
Note: there is no such thing as PHP 6. PHP versions jumped from 5.6 to 7.0. Why? Well, it's a long story. TL;DR: It doesn't have to make sense, just accept it.