Go to the Start button and open Bullzip folder -> Bullzip PDF Printer Option.

Change the path in File Name to the GreenFolders Dropbox.

Example:

3.8 Users: C:\Users\Sally\GreenFolders Dropbox\<smarttitle>.pdf
3.9+ Users: C:\Users\Sally\AppData\Roaming\GreenFolders\GreenFolders\GreenFolders Dropbox\<smarttitle>.pdf

Uncheck the Confirm Overwrite.

From the Dialogs Tab:

Change the radio button to Never on both Save As - Dialog and Settings – Dialog.

Change the radio button to No on the Show Document. Click on the Apply and then Ok.

Now when you choose the Bullzip printer it will print directly to the GreenFolders Dropbox.