That doesn't apply to the Sony T1 device. To those others listed, yes it does but the Sony reader is not an iPad, tablet, mobile device (aka Smart Phone) or a PC. Have you registered your Sony & bought books through the Sony Store on the device? If so, you should be good to go.
Buying your first book through the Sony Store on the device makes you register to Adobe Digital Editions.
Click on the Library link, find your library, it's a good idea to save it as a favorite by clicking on the heart icon, enter your library card number and password and then find your book.