Since you probably have the USB PLM, you might want to look at using Home Assistant for the control of your remaining devices. The integrations created for use with Hubitat require you have an Insteon Hub, and for full functionality, it also requires a separate always on computer to run Insteon server and socket listener programs. The Home Assistant Insteon integration isn't as fast or reliable, but it works. It also has some tools for adjusting device settings that we do not have here.
Depending on your skill level, you may decide that Home Assistant is the better choice for you as a hub, but if you're not versed in YAML then you'll find complex automation is quite a bit more difficult with Home Assistant. Therefor, you could run Insteon, Home Assistant and Hubitat just fine together as you transition away from Insteon by using a community app named Home Assistant Device Bridge. This would allow you to add a very simple Home Assistant installation via a VM (they have several ways to do this now and they're all quite easy), and then using HADB, you would bring those Insteon devices into Hubitat from Home Assistant.
Another option is to just get an Insteon hub and use the integration here. It's not too hard to setup, but again you will need to have an always on computer to run the server if you want full control with Insteon device status in Hubitat. I actually kept and even expanded my Insteon dimmers using this Insteon integration for Hubitat, and combine their control with Lutron Pico remotes. I also run Home Assistant with HADB, but I don't use HA to control my Insteon devices.
Hope this is helpful. @marktheknife is correct. There's no simple way to integrate Insteon. The HA method is darn close to what one might consider easy, but it's not without its shortcomings too.
