The last option on the DocuSign app menu(accessed from the dashboard) is 'Library'(P1). DocuSign app users have the option to access a library where they can save a document onto their device.
When the the "+" is tapped(P2), the user will be prompted to add documents from various sources(P3) including, but not limited to:
Box
Google Drive
Dropbox
Camera(the device will open the camera and prompt the user to take a picture of the document they want to use)