The explanation on the website seems perfectly good. It's a system that can go from something like DropBox (automatic sync of files with a cloud) to Git (version history, commits, manual pull/push, conflict resolution). I don't know for sure, but it seems you configure which features you want to activate during setup.
There actually aren't any features to activate, the goal of Darke Files is that different users of the same repository can work at different ends of this sync <-> version control spectrum.
Does this help?