Hi
It gets used throughout the functionality
In BRM - Business Role Management - you configure the default connector for action to use. For example, you specify the default for actions so when you maintain authorisations it knows which system to launch.
When it comes to risk analysis, you can have a specific one you use and the drop down will default it. But you may have other connectors as you run risk analysis over multiple systems.
If you only have one connector set it as the default.