Why can’t I open the e-book on my desktop computer?

You must install a reading software on your desktop. Here are some reading software for desktop computers: 

• Calibre E-book 
• Adobe Digital Editions 
• EPub Reader for Firefox (this is a Firefox Add-on) 

Note: For macOS users, the Apple Book program download the e-book directly into the Apple Books library. No need to install an additional reading software. Select on the PDF version to download the file to your Mac. It will open in Apple Books.