Before you can set up your node on a device, you'll need to create one in Sense to create a Node Key.
In the "Devices" tab, go to the "Nodes" sub-tab
Click the "Add Node" button
Enter a name for your node
If you already have cameras to assign, you can click "Save & Continue to Assign Cameras", or click "Save & Close"
Find your newly created node in the list. Note the Node Key which you'll need to run the node.