I have followed the lesson and set up tunnelling as suggested but when accessing the web page I get:
Deceptive site ahead
Attackers on 0.tcp.ngrok.io may trick you into doing something dangerous like installing software or revealing your personal information (for example, passwords, phone numbers or credit cards). Learn more
Should I be concerned and how can I prevent this?
Which web browser or anti-virus are you using?
I can ensure you that you don’t need to worry about that warning message. If it was a weird URL that someone sent you or you clicked online, I would double-check and be careful. However, this is your own tunnel running a web server that you’ve created, you don’t need to worry about that warning.