In order to start an arming scenario just click on the top right menu --> Click on "Alarm's scenarios" and select the scenario you want to start.
For more information check the tutorial: https://www.youtube.com/watch?v=5NiLvOZBKqA&list=PLlaDNT-XSIbcAbndD7ENMUMoSZXDKOm0o&index=3