@Alicat 

borrowbox is the name of the library app, from the appstore, then you sign in with your library account.

your local library's website should have all the info, even if it's not the same app, they will have one.

I joined the library online, downloaded the app and signed in. Now I can borrow ebooks (audio and ones you read) through the app. I can reserve things that are already out and they email me when they're available. After listening you "return" the ebook and it deletes from your download file.