You must have the Adobe Digital Editions downloaded and installed on your computer before you download your eBook.
A dialog box will open asking if you want to Open or Save the file.
If you want to read the eBook without actually downloading the file on your system, choose Open. The book will open in Adobe Digital Editions.
If you want to download the file on your system, choose Save. Another dialog box will open asking for location where you want to store URLLink.acsm file.
Select a location on your system and click Save. A file named "URLLink.acsm" will download on the selected location.
Right-click the "URLLink.acsm" file.
Select 'Open With', and choose "Adobe Digital Editions".
Click "OK". Adobe Digital Editions opens and downloads the eBook.
You can simply double click on "URLLink.acsm" file to open it in Adobe Digital Edition.