You must register your environment for an API key here:

https://www.adobe.io/apis/documentcloud/dcsdk/gettingstarted.html

Features:

• Embed PDFs, with support for full-sized windows, sized containers, in-line display, and lightboxes 
• Full support for create, delete, update comments with the option to save.
• Customizable toolbar to enable or disable the left-hand panel, comments pane, toolbars, print, and download options