Vendors have different levels of restrictions for ebooks. Some can only be read by one person at a time online, while some you can download the entire book. Some even allow for unlimited seats.
As you log into a book through the "Access for Bloomington" button in IUCAT, keep an eye on the book's details page to see what kind of access it allows, so you can know how easily you might be able to read this item (especially if you need it for teaching or your own schoolwork.)