I've installed Stellar Library on my tablet but all I get is an empty bookshelf.

Content will appear in your library once you have entered your login details. You should be sent an email with your login details by the organisation that is sharing content with you. If it is your own library check for new content by pull down the bookshelf.

If your bookshelf remains empty and it is not your own library, please check with the librarian to see whether you have been granted access to the folder that the organisation is sharing the content with you.