Can't open the App
Most likley you will see this alert, that the app is from an unidentified Developer:
To open the app, you will have to open your system preferences:
Now under the "General" tab, click the lock icon and enter your password.
Click on the "Anywhere" option in the "Allow apps downloaded from:" section. You should now get the following message. Simply click the "Allow From Anywhere" button.
Now you can close your system preferences and open SCD just like any other app!