If you have Hubitat Package Manager r(HPM) running all you need to do is select Install option and search Homebridge v2. If you dont have HPM installed you can install Hubitat/Homebrige manually. Check out the authors github
Another option that requires no custom code on Hubitat is @dan.t’s Maker API plug-in for HomeBridge. I have been using it for a long time with no issues.
I read through the comments, and as far as I can understand, there is still no way of backwards communication from Homebridge to Hubitat? I have a few Sonoff Wifi devices with factory firmware, and can't add them to Hubitat. I tried through Home Assistant, however it wasn't working well (chrashes, or updating breaks things...), and I tried adding my light switches from Homebridge to Hubitat. Note that I do not own any Apple devices, and I am not planning at all.
Correct, communication is from he to hk or he to ha to hk. Now you can use virtual switches to make HK do something on HE. Such as have HK open a lock on HE.