At PBI.org click the Sign In button in the upper right-hand corner of the screen. (This button might also say Your Account if you are already signed into your account.) Sign into your account using your email address and password.
Once signed in, you will be taken to Your Account home page. Here, click the tab that says Classroom.
In your Classroom you will see the publication title that you purchased. Click the title of the publication and on the next page you will see options to download the book files.