How do I open ebook? redirects me to webpage instead of opening.

I downloaded ReaderDC so that I can read my downloaded library ebook.  I double click on the file, it opens Reader DC but not my file.  I try opening my file from within ReaderDC and I get redirected to the webpage marketing Digital Editions... Opening it in Digital Editions only provides a cover page saying I need ReaderDC, no content.  Around and around in circles. no traction!  help.