API - Help to get PDF file generated by API call and save to database

Hi, I’ve already learned a lot developing with Bubble, but I still find it difficult working with APIs.

I’m using API from to generate a PDF file from a page of my app, I set up the call to generate the file successfully, but I don’t know how to get the file and save to my database.

The instruction from the site is: “We will send generated pdf document (encoded with base64) to your provided callback URL in this structure: *{“document”: “…”}”

So, I need to set up an end point (the callback URL) to receive the generated file and save to the database, but I have no idea on how to do that. help please!