Your Betfair API-NG app is allowed to place bet using the Live or Delayed Key. It does not want you to use the live key for testing\demo\simulation, meaning you can get into trouble if you abuse the Live Key for data without betting. Use Delayed Key for the above.

Your app is allowed to place bet using the Live or Delayed Key

Betfair API-NG - Filter by Time frame and competition. Grid alternate color background by market group.