AdventureCube is a Fork based on SugarCube which is a free (gratis and libre) StoryFormat for Twine/Twee.
All Sugarcube Downloads and documentation, as of now, are valid and can be found at SugarCube website. AdventureCube specific documentation will follow as development goes on.
This Fork is currently very early in Progress, and is barely any different from SugarCube.
If you want to build AdventureCube from scratch, then it simply follows the same instructions that SugarCube's Buildprocess provides.