Matt EgenMostly had problems with using some of the code that you provided as the inclusions didn't work in the Azure Function code, my inclusions ended up looking like this
#r "Newtonsoft.Json"
#r "System.Text.Json"
using System;
using System.Net; //almost everything
using System.Text; //class encoding
using System.IO; //streamreader
using System.Text.Json.Serialization;
using System.Net.Http.Headers;
using System.Security.Headers;
using Newtonsoft.Json; //parse json
I was also completely new to C# and Azure Functions, so I really wasn't aware on how to include specific libraries into Azure Functions. Especially since I could not find a way to include an assembly module in the documentation that actually works. I don't even know where I saw #r for the first time, but I had to guess the correct values for me to be able to include specific libraries - like System.Text.Json.Serialization.
So I re-coded the authentication, the BootstrapTLD and the QueryRDAP to work with only the base System libraries.
Most of the code on GitHub worked after I found that I could do #r "System.Text.Json"
So issues purely on my side as I could not copy/paste any of your things and ended up fixing it by redoing everything step-by-step until I figured out what was going on.