It defaults to record automatically. To change this, load it up, and you should see a large window that says 'Video Capture.' Under this a little way down you should see 'Highlight Clips' and 'Session Record.' Click them to turn them off.
For manual record on/off hover mouse anywhere in 'Video Capture' till you see a small gear in the lower right corner. Click it for settings. Then navigate to Hotkeys, and set Stop/Start manual record to whatever is convenient.