New (Potential?) Partner Question

Hey Team!
I’m the owner of a 3rd party custom software development shop for SMB. We don’t have a software product. Instead, we create custom solutions for our clients. Because of this, I’m not sure where/how we fit as an Infusionsoft Partner (we currently don’t have a product). I’ve submitted a request via dev site new developer - Powered by Keap and got an email reply. The scheduling link in the email (AppointmentCore - Error - AppointmentCore) is broken and there’s no URL for the “Partner Packet” in the email. Not sure if the form I submitted is still valid?

Here’s my Question
We’ve got a client who wants to build an integration between SignNow (similar to Docusign, but cheaper) and Infusionsoft. We’ve written the code and it’s working (our dev on the project loves your API documentation!), but we need help figuring out how to build the OAuth portion since our app will be headless (no GUI) and only for one customer.
What’s the right way of building this to integrate with your platform?