Request for Feedback on API Quickstart Guide

I put this (very work in progress) API quickstart guide together to help developers integrate my company's API into their workflow. It is not designed, just imported from markdown into a Google Doc into a pdf. I was hoping to get some feedback on how it's put together and suggestions for improvements. Many thanks in advance!

https://www.dropbox.com/s/bqvl6h9mskdlqbs/Onfido%20API%20Quickstart.pdf?dl=0