The Libby app is not available in the Amazon app store for Kindle Fire devices. However, Kindle Fire users can take advantage of the webapp version of Libby, using the Silk browser on the Kindle Fire device.
Just visit the Libby webapp on your Silk or other browser, and then follow the prompts to add a library and library card to Libby. Once configured, the webapp version of Libby will provide a mobile-friendly experience that approximates the mobile app.
