Hey Peter, I hope you're going well.
I've looked into this. The error is due to a recent update to the Binance REST API and how they manage the keys.
They are now using a Config Parser to ensure that the Keys have their HMAC or RSA encryption correctly applied.
While I agree with their overall intent, it has invalidated this part of my series.
I'll be releasing a new series over the next week or so on Medium and YouTube to help out.
I apologize for the confusion - troubleshooting can be an absolute pain <3