Not all titles can be downloaded in your Libby app. Check your "Loans" to see if the titles you checked out can only be streamed. Find loans by tapping the book icon at the bottom of the screen.
Loans with a card-and-checkmark icon are downloaded on your device for offline use. Loans with a cloud icon or aren't downloaded on your device and will be streamed when you open them. These titles require an internet connection to read or listen to and don't take up space on your device..