Go to Schedule > Area Settings.

In Automatic Arming, you may turn Disarm and Arm on or off for each area. If both Disarm and Arm are switched on, the selected area disarms at the schedule Begin time and arms at the schedule End time automatically.

If your system does not use automatic arming, you can use the Closing Check feature to ensure that your system is armed by an authorized user at a specific time.
To enable Closing Check, press Area Settings. Select Remind me when my system is not armed at the scheduled time, then press Save.