You need the Free Pascal Compiler (FPC) to use our engine. We always support and advice the latest stable (from freepascal.org) release of FPC (currently 3.0.2). Usually, we also support a couple of older FPC releases.
You may also find it comfortable to use Lazarus, which is an IDE (editor, debugger etc.) built around FPC with a visual classes library (LCL). Our engine components can be used together with Lazarus forms (although we also have an alternative window classes, independent from Lazarus LCL). Currently, we don't have any special requirements on the Lazarus version.