From version 2.2 you are able to open documents in mobile apps, preview them or use options to share them via other apps, download them to your device or store them to cloud storage apps that you may be using (Google Drive, Dropbox etc).
To begin, open a deal and go to documents tab (3rd option on bottom navigation). Click on the file you would like to open and it will render the preview in the next screen.
While in preview screen you have option it top right corner to share the file by using other apps you have on your phone, such as email apps, messenger apps, or to store the document as a File on your phone or cloud storage service (Google Drive, Dropbox etc.):
After share button is clicked, you have options to perform on the document. You can share, save as File to your phone or store document on cloud (Google Drive, Dropbox etc.)