To make Alarm.com work via Homebridge to Apple Home is a little bit complicated. The main issue is that even when you install the Homebridge Plugin for Alarm.com, you also have to find the 2 Factor Authentication cookie and put that into the user interface.

The way to do this is pretty obscure, nearly as bad as making MiHome work. But basically:

1. Login to Alarm.com with a browser
2. Then you have to figure out how to dig cookies out of your browser
3. For Safari, you have to turn on the Developer menu by going to Safari > Settings > Advanced, and at the bottom you will see Show Developer Menu
4. Now you have to find the Cookies section which is buried in Safari > Developer > Show Web Console > Storage > Cookies
5. Now go through the table of the many cookies and look for twoFactorAuthenticationId which should be a 64-character hex string of numbers and letters.
6. Squirrel this away in 1Password and be careful

Enter into Homebridge to add the 2FA Cookie

You will have to get to your Raspberry Pi or whatever is running. In general, it publishes homebridge.local so just go there in your browser:

1. In the Homebridge, click on plugins > Homebridge Node Alarm Dot Com > Settings
2. Enter the username and password
3. Click on Use Two Factor And then copy that 64-character monster id there. Note that you had better make sure your Homebridge is secure because this will give access to everything

Apple Home Configuration of Alarm.com

OK, get ready for a lot of work, but basically, you should now go to Apple Home and you are going to be alot of swiping:

1. Start Apple Home
2. Go to the Hamberger at the upper right and select Default Room
3. Then at the top of the screen will be a list of Contact and Door Sensors, press there
4. Now you will have a lot of sensors (we have 50!), so for each one, you click on it
5. Here you can change the Display As to Door if appropriate or window. I did find that this doesn't work most of the time, it seems stuck on the default Contact and does not allow a change.
6. Then go to Status and Notifications and for Doors, the logical thing is to choose Any Time and When No One is at Home.
7. You have to go through the entire list for this and your finger gets tired!

Disable NordVPN Thread Protection to get to Homebridge on MacOS

One interesting thing is that if you try to get homebridge.local on a Mac, then it doesn't seem to find it, but the Bonjour access works find on iOS but not on the Mac. But on our UniFi setup, we have the default localdomain working, so I could get access that way.

But this returned a null website, so I tried to disable the VPN and I've had problems with VPN access but it was not the DNS which makes sense since Bonjour doesn't use this.

But when I disable the NordVPN Thread protection then it worked fine