Hi, well, the paper manual is available when you buy the product, or if I remember well, also as "standalone" item in the Arturia store. I don't think there's any pdf around...
You could also ebay for the original (or copied) 2600 manual, just to have a better idea of the hardware instrument.
My advice is: it's a demo, so have fun listening to the presets (many of them are really inspiring and beautiful, in my opinion) and trying to tweak some knobs...
something will happen! ;-)