You can add a button to the PURL page (Online Viewbook) that is a links to any outside site easily! Just head to the Viewbook Builder under the Content tab and follow these steps:
1. Click + next to Navigation
2. Create a page name under Label
3. Insert URL under URL, choose if you’d like this to be displayed on a mobile view and enable a specific group to be able to view page.
NOTE: When you’ve successfully completed building this off-page link, the link will be visible with a black arrow in your Navigation menu and will appear as a standard menu item on a PURL page.