This is a sandbox project, which contains experimental code for developer use only.
This module is meant for grouping content types on the node/add page.
A quote from the content type groups module which explains very clearly what this module will do:
Let's say you're organizing your media collection. You have the following content types: book, movie, audio, article (for your blog about your collection), and page (for some static content).
Create a content type group called Media and add the book, movie and audio types.
When you go to node/add, you will see the media content types grouped together, and your page just got a whole lot more comprehensible!
The admin interface (drag and drop and adding groups) is not working.