@ThompsonIrrigation I think you need to plug the adapter into the GFCI you mentioned is present. Similar to the steps I took.
Refer to those instructions here:
After mounting the outdoor enclosure, I plugged the adapter into my outdoor "and" covered GFCI outlet (located about a foot below where my Rachio Gen 2 is mounted). The wire from the adapter pokes out from underneath the small hole beneath the cover of the outlet. I ran the wire into the outdoor enclosure via the same hole I ran my zone wires into. I had a lot of slack in the adapter wire, so I gathered them up into loops within the enclosure and tied them together. Then, I plugged the adapter wire into the power outlet of the Rachio Gen 2, Next, I installed the Rachio Gen 2 (naked - without its supplied cover) into the outdoor enclosure being sure to pull through the zone wires through the hole in the bottom of the Rachio Gen 2 and attaching them appropriately. By about this time, the Rachio Gen 2 was nearly done in its power up and WiFi setup process.
If you have direct power (no plug) for the Rachio Gen 2 (or the one you're replacing), then you'll place the adapter inside the outdoor enclosure with the direct power lines getting connected within the small box inside the enclosure (located in the bottom left corner).
Hope that helps and clarifies. hi5