If you haven't followed from the beginning the homebridge buddy development and the earlier homebridge-indigo plug-in from Webdeck, it's understandable that it can be hard to follow and setup. Anyway, I'll try to help get you started:
Homebridge Buddy automatically creates a home bridge called "Homebridge for Indigo" that by default is running on the same computer as your indigo server.
You then edit the Homebridge for Indigo Device to select your indigo devices that you want to work with Homebridge/Siri. You'll also need to configure the IOS Home app to use the "Homebridge for Indigo" device. A tip: I've found at least for my setup, to always reboot my computer after making changes to the Homebridge for Indigo device. In theory you do not have to reboot, but for my setup, if I don't, then often Indigo becomes unresponsive.
You can find some information on setting up homebridge buddy in this thread "Homebridge Buddy Info & Updates"
viewtopic.php?f=204&t=17405Also, in the Homebride-master folder that come with the plug-in, check out the "*.adocs" files in the docs subfolder, there is documentation there.
Good Luck.