Hi

I dont know how the tutorial website is generated, but:

https://developer.wordpress.org/secure-custom-fields/how-content-works is 404 and is linked from https://developer.wordpress.org/secure-custom-fields/

Installation (and quickstart) seem to be 301 to https://developer.wordpress.org/secure-custom-fields/welcome/installation/, but the how-content-works is not 301 to welcome path. Also if I manually change url to https://developer.wordpress.org/secure-custom-fields/welcome/how-content-works/ its still a 404.