Once the book is in your ADE library, you can use one of these methods to convert it to a standard PDF. Method A: Using Calibre (Free & Open Source)
Before you can convert anything, you must have the actual book file on your computer. how to download adobe digital editions to pdf
Open ADE, go to the Help menu, and select Authorize Computer . Log in with your Adobe ID. Once the book is in your ADE library,
Calibre is a powerful, free tool, but it requires a specific plugin to handle Adobe's protection (DRM). go to the Help menu