If you are logged in and navigate to Posts > Categories, you will not get an explorer-like tree from Real Category Management. Unfortunately this screen is not supported and not in scope of Real Category Management. The plugins’ philosophy is, to create an explorer-like view (as you know from Windows Explorer or Mac Finder) directly beside to the items itself (in this case posts and products). A tree in this view wouldn’t make much sense.
What are you missing in the explorer view? Please let us know via our support form.