I am a developer for a call center. We currently have a number of clients that we have Shopify integrations with for placing orders. The REST API works for us when our client is using a 3rd party payment gateway such as Authorize.Net or Stripe as we can integrate with the 3rd party gateway ourselves and include the authorization response from the payment gateway in the post to the orders.json endpoint.
Now we have a client that has their shopify site set up to use the built-in payment gateway and can't seem to find the right direction to go for implementing a solid integration.
Here is what I have tried so far:
I have created an app in the devloper portal, converted it to a sales channel, requested access to Shopify Payments
The request was denied for the below reason: "What you are describing seems more like a Custom Checkout, which we cannot approve."
What do I need to do to be able to post orders into our client's shopify site using Shopify's built-in payment gateway?