Adobe Digital Editions (ADE) is Digital Rights Management (DRM) software that many publishers require to download their eBooks for offline reading. ADE ensures your "borrowed" eBooks are automatically "returned" and stop working after a certain number of days/weeks. ADE requires the use of a separate Adobe account.
ADE is available for both the Windows and Mac operating systems. Download the installer from Adobe's site and run the program on your computer. Once installed, open ADE to read the "Getting Started" guide. Any eBook you check out will be downloaded for reading into ADE.
Technical support questions about ADE and Adobe passwords should be directed to Adobe's Customer Care.