API and OAuth 2.0 Integration

I need assistance building api calls and responses to both UPs and Fedex accounts.
You need to be an expert who can go through their documentation and provide me with the exact api calls and responses I need for an app I'm building in a low-code platfrom (bubble) that will make the api calls and responses.

I am building a prototype that will be used in production but once that is built and tested I would extend the project to build the actual application in node.js or java or golang.