Hi @lukejamison! If you haven't already, I would go ahead and add https://oauth.retool.com/oauth/oauthcallback as an authorized redirect URI in the configuration of your client on Google's side. Note that it might take a little bit of time for your changes to actually go into effect.
It's not super clear but this is actually how our docs recommend doing it! Let us know if you run into any additional issues. 