Yuzu eReader funktioniert nicht

Yuzu is a learning platform that lets you read and interact with digital content from the convenience of your iPad or iPhone.  Interactive Learning - eTextbooks can include videos and other multimedia content and links to related websites, to make the learning experience richer and more engaging.  Simple Navigation - Search keywords, phrases, and figures throughout all of your digital content.  Quickly jump to a location by typing a page number. * Create highlights, notes, and bookmarks.  Travel Lighter - Replace multiple textbooks with one app where you can access your course materials from a single, beautifully organized interface.  Read On-the-Go - With course materials always at your fingertips, you can read and study wherever you are.  Highlights, notes, and bookmarks automatically sync across all of your devices.  Study Smarter - You can highlight and add notes to your eTextbooks.  Plus, you can easily adjust the layout, font size, and zoom to make reading easier.  Your changes are automatically saved and made available to all of your apps. • Listen to your books and learn on the go with Read Aloud. * Zoom fixed format content or adjust the layout and fonts with reflowable content. * Download your digital content for later reading and adding notes while offline.