Hi,
The Crafty engine is included, it is the default computer opponent, but it is not the latest Crafty version. You can find the latest Crafty engine at www.craftychess.com
You can use it in Crafty GUI just as any winboard engine using Engine>Add new engine menu.
If I'll find time for it (as it takes considerable time), then I'll make an updated Crafty GUI version that includes the latest Crafty version.
Valters.