To access your Note Library first open the project to which you've assigned your notes.
Next, navigate to the Airstory icon in the upper left-hand corner of the project/document view:
Click on the Airstory icon to lock open the purple navigation bar.
Click on the 'Note Library':
The 'Note Library' will open to the current project, however, you can access 'Archived' or 'Unassigned' notes or those from 'All Projects' via the drop-down menu: