The windows version is a self-installing application.
The Macintosh (OSX) works with OSX version 10.6 or higher.
The java version can be run on any computer with Java and allows for environments where the user doesn't have administrative privileges to install applications.
Step 4 - License Activation
When your license has been purchased, an email will be sent to you, including a download link for the Professional version and a Registration key. Please allow 24 hours for activation.