University Library purchases ebooks through a variety of vendors/publishers. For example, Oxford, Cambridge, JSTOR, DeGruyter, and Project Muse.
When you click on an ebook link from Library One Search or the library catalog, you will be taken to that vendor's platform.
While the platforms all look slightly different, the functionality should be the same: you should be able to read the ebook in an on-screen viewer, download chapter-by-chapter, and search within the book.
Because of DRM (digital rights management restrictions), you most likely will not be able to download the entire ebook at once.