The Setup folder contains files from others or from my older mods that I might convert or build upon. It might contain, for example, an obj or a blend file that has a model I want to convert into a survivor. I would also include the web page or text file with authoring credits and screenshots of the model. I would make a text file here for development notes to myself, such as who requested the model and problems I found.
Create the Setup folder:
Within the "workspace" folder, create the development folder: 01 Setup
Note the "01" at the start of the name. I use that so the workspace folders are listed in this order: 01 Setup, 02 Source, 03 Release