ProBundle versions of HubConnect v2.0 from behind the "free wall" have been released. The difference is that ProBundles don't expose the code — if you need to explore it, it's all available at HubConnect.to.
You've never run HubConnect before. Install both of these on your Hubitat hub.
You already have Server + Drivers running on hub #1. On the second hub, install these instead.
Home Assistant takes the place of a second Hubitat hub, so you won't need the Remote bundle at all — just Server + Drivers here, then head to the HA setup guide.
Need the raw bundle URLs on their own? They're the same three files — Server, Remote, and Universal Drivers — just grouped above by which two you'll actually use.
Select Bundles from the main menu and click Import Zip in the upper right.
Hubitat — Bundles screen
Select the Download from a URL tab, check This is a private pro installer bundle, then paste in either the Server bundle URL or the Remote bundle URL above. Click Import.
Hubitat — Bundles import screen
Hubitat — Bundles result screen
UniversalDriver URL, or use Hubitat Package Manager for the Universal Drivers instead.