Hey Nathan! Thanks for reaching out on the community. This article explains how to configure an oauth2 connection in integrator.io. The details required by integrator.io can be found on this xero's article about oauth2. Try those steps and let us know if you run into any issues while configuring.
Yes, we did get this running. In the end, it was an Oauth2 connection but something in the way we first "set it up" caused it to not connect. When we started fresh it was all good.