Download the free ebook at THIS LINK

  and the ebook will be stored in the Downloads Folder.

  If you have iTunes installed follow the suggested procedure.

  If you prefer a different App, choose one from the Apple Mac App Store.  
I have only seen the "Epub Reader" (with the brown logo)

in action and it seems OK.

  The usual controls of Contents, pages Forward → and Back ←
  and Settings, and Choose another ebook are somewhere.
  (Sorry, that's all I know about that.)