First, it appears your version of the Alarmserver code is using an old DTH that doesn’t support the on/off switch function. You need that for this to work. I don’t know if you have a Honeywell or DSC panel - but both of the current versions ‘panel’ devices show up as on/off buttons. (I think this was one of @Xero’s edits in his branch) Turning the Stay Panel ‘on’ arms in stay, Away ‘on’ arms away and turning them off disarms… I have a DSC panel so I use @Xero’s build with the @rtorch edits because it supports my panel AND runs on a RPi with Python 3.8: DSC -> EVL-3(4) -> Alarmserver -> Smartthings
So do a search on AlarmServer and find the most current version that works with your panel and upgrade: https://community.smartthings.com/search?q=alarmserver
Next you perform this STHM workaround by the ActionTiles community: https://support.actiontiles.com/knowledge-bases/8/articles/8170-how-to-use-new-smartthings-home-monitor-with-actiontiles
So now that you’ve done this, in the automations you created in the previous step for Arm Away, Arm Stay and Disarm - Add turning on or off the appropriate switches respectively. (I use WebCore for this part to add in some advanced checking logic, but it has the same effect and you don’ t NEED to do that, it’s just nice to have…)
Then Setup STHM.
If you want, you can completely ignore your sensors so STHM never actually alarms - I personally use a the SHM Delay virtual sensor ([Release] SHM Delay Version 2.0) triggered on my doors so it does alarm but only after the DSC would anyway.
Now what you have done is you have just tied STHM to your Alarmserver Panel. When you hit the arm / disarm / stay on the home page of ST, your Alarmserver will follow.