The device handler just allows SmartThings to communcicate with the keypad. Programming codes, arming/disarming etc are all features that are provided by SmartApps like LUM or RLA.
You will need to create users and then assign actions on what needs to be done when a user unlocks (disarms) or locks (arms) the keypad using the programming code. If you’re trying to synchronize it with STHM refer to this post.