Hey James,
The downloaded file should be named something like URLLink(#).acsm. If you're using Chrome as your browser, you'll simply see this file download. Open the file using Adobe Digital Editions(
www.adobe.com/products/digitaleditions/) and it should start the download of your e-book automatically.
Let us know if you're still having trouble.
Best,
Matt Mapplebeck
Student Services Associate
Manhattan GMAT