I’ve written a short guide showing some Workflow between Zbrush and blender.
I’ve also tried to explain how to make GoB addon working fine.
You can find the guide here and the complete GoB addon here
Note : In the guide, I’ve faced some UVs problem generating normal and displacement map.
The problem was that Zbrush doesn’t deal correctly with UV island that are out of the UV space. So if you plan to use Zbrush to generate maps, you need to make sure that you’re whole mesh UVs are in the UV space. If you want to isolate a part of the UVs island, just scaled them to a super tiny size and put them in a corner of the UV canvas.