‘Only when mode is Home’ refers to the ‘location mode’. By default your SmartThings location has three modes, ‘Home’, ‘Away’ and ‘Night’. These aren’t really named with shift workers in mind. So ‘Home’ typically means it is daytime and people are up and about in the house and any security system is disarmed. ‘Night’ might mean you have all gone to bed and you have a partially armed security system that detects intrusions but allows typical night time activity without setting off the alarm. ‘Away’ would mean the house is empty and any security is fully armed. It is up to you to set these modes, typically using Automations. They can also be set manually, and you can add and delete and rename them, though bizarrely they are hidden in ‘Manage Location’ which is off the three dot menu on the mobile app dashboard.
If you want to use them, which is entirely your choice, you might perhaps set the location mode to ‘Home’ at a fixed time in the morning, or perhaps when you detect motion in certain rooms during a particular time period. You might also set it in an arrival automation. You might set ‘Night’ at a fixed time in the evening, or perhaps when you don’t detect any motion in certain rooms for a while. You might set ‘Away’ in a departure automation.