Some ebook providers will let you print a number of pages – quite often this is about 10% which fits with UK copyright law but sometimes it can be more or less. The amount you can print is different for every title and is decided by the ebook provider. This is not something that the University Library can change.
The number of pages you can print or (download to keep) will be different for every title. For some titles you will need to choose a specific page range to print, for others you can download a full chapter.
If you select a page range rather than a chapter, be selective as you won’t be able to print more than the stated allowance.