Access denied when trying to use SP-API to call `getRates` for Amazon order

Does anyone know if you need PII access to call `getRates` and other similar Shipping API v2 functions via the SP-API?

I’d like to call `getRates` etc to get shipping rates and then purchase a label for existing Amazon orders. I don’t have PII access, but my understanding from reading elsewhere is that if you supply an Amazon order ID, Amazon will pull the address info from there and will get rates etc (so basically I never “find out” the customer’s PII because I never need to know).

But no matter what I do, I get an access denied error.

Meanwhile I thought I read that we need access to Amazon Logistics, and after some back-and-forth with Amazon, they said I need to open a developer account. And reading the documentation there seems to indicate that Amazon Logistics is for shipping orders placed on third-party websites, which is not what we want to do.

Anyway.. so the point is, if anyone has any input on how to use the SP-API to get rates and generate labels for our orders, I’d really appreciate it!