Louis helped me understand the issue. The REST API is currently in BETA and does not allow calls from production environments. However, he did point me towards how I can achieve what I was trying to do via the XML API.
Thanks.
I didn't get a notification about your response, but yeah, I would love to have a call. Here's my email: [email protected].
I am connecting an admin user however I can't tell what you mean by a non-production company. We are not in a sandbox.