Rachio 3 - how to install the rain sensor?

Just bought a Rachio3 from Costco to replace my older Toro Turf Pro. I just finished wiring the Rachio 3, it works perfect. I have not wired the rain sensor yet though. The old one was contected to a + and - on the rain sensor. How should I wire this into the Rachio?
Thank you
New Rachio3 Member

I assume that 24VAC is for the power converter?