Q) Why is the file I download in a .zip file format? I thought I was downloading an audio, video or ebook file.
A) Zip (.zip) files are files that are compressed to decrease the total file size. Files are compressed to reduce the amount of disk space needed for storage, to reduce download times, and so on. Note that after you obtain a .zip file, to view or use the contents of the .zip file, you must uncompress (unzip) it. For more information about .zip files and how to use them visit Microsoft. Link to Microsoft.com
Q) How do I install an .epub file on my Apple device - ipod/iphone/ipad?
A) After you have downloaded and unzipped the .zip file you can find support for your Apple device here, Link to Apple Support
Q) How do I install an .epub file on my nook device?
A) After you have downloaded and unzipped the .zip file you can find support for your nook device here, Link to Barnes & Noble Support