On the System Manager panel you'll find some useful information and also a few extra settings.

First there's the cron command string that you used when you installed SmartDD.

Then there are the global product settings, max downloads and secondary max downloads, plus the redirect URLs.  The max downloads are the number of downloads you allow for each customer / product, and I suggest you leave it at 3 to minimise support emails.

After the 3 downloads have taken place, your customer will be redirected to a page that instructs your customer to contact you.

 
When they contact you, you can then decide whether to allow more downloads of their order or not by resetting the download counter.

The secondary max downloads has been added as a feature to do a different redirect after that number of downloads has been reached.  This would be really useful if someone had shared their download link in a forum, as you could have the link redirect to your home page.

You then have a permanent back link to your website! 
Finally, there are the user settings.  Here you can define what the admin user login should be so that it doens't have to be the default "admin" if you don't want it to be.

You can also set your admin email address for SmartDD to communicate to you through.

Lastly, you can paste your SmartDD.com affiliate link into the box.  Then every email that goes out has your affiliate link at the bottom of it and is a potential additional earner for you if your customer follows it and purchases SmartDD.

You can get your affiliate link in the members area at http://www.SmartDD.com/