How to use AccountKit on Asp.Net Core?

Question

Facebook

I can't figure out the question "How to use Facebook's AccountKit on Asp.net Core without connecting the SDK?". Everywhere examples are shown using SDK from JS. I need to do it on Backend.
I found a solution from this dude, but it's not clear what code should be specified in "MyClientAuthCode" https://github.com/betalgo/FacebookAccountKit.