On the home screen and template dialog of SmartDraw, click on Menu in the upper right corner, select Add Service, and choose Dropbox®.
Next, login to your Dropbox® account.
When prompted, agree to let your SmartDraw connect to your Dropbox® by clicking Allow.
You can now save any diagram to Dropbox® using Save As in the File tab.
Alternatively you can also add a new service like Dropbox® right from the Save As dialog. Just click on the logo.