I release my mdmod files you apparently somehow got hold of into the public domain (CC0 1.0). rpd-module is \copyright 2017 by Michael C. Davis and released under the LaTeX Project Public License v1.3c. The titlegraphic included as an example is by sbzine https://www.flickr.com/photos/sbszine/, released under CC BY-NC-SA 2.0 license. That means you can't use this image in commercial products, and you must credit sbzine if you use it. The OSR-Logo is \copyright 2011 Stuart Robertson, released under CC BY 3.0 license. You can use it in your works as long as you credit Stuart.
I assume you're using these files on a recent linux distribution. You should be good to go, if you install:
- texlive
- pandoc
Get the rpg-module package from https://github.com/slithy/rpg_module. You should install it in one of your texmf folders. Running the command texhash should make it available to your texlive installation.
Finally copy the mdmod folder to a directory where you want to work on your project.