The Developer tutorials for creating features, etc. are centered on API Keys. Everything links to this page for how to create an API key,
https://developers.arcgis.com/documentation/security-and-authentication/api-key-authentication/tutorials/create-an-api-key/
The tutorial page gives INCORRECT information. It says to create an item, then click Developer credentials > API key credentials. However, there is no "API key credentials" option.
I have tried this with my fully-privileged work account and an ArcGIS Personal account.
FIRST: It is very frustrating to be led to invalid training material.
SECOND: All tutorials seem to be API Key centric, even though Client ID/Client Secret methods exist as well as programmatic sign-in to obtain a token, but I don't see where these are covered.
THIRD: If you sign up using a different email address through https://location.arcgis.com/ then go to Content > New item > Developer credentials, you then have "API key credentials" But what good is that going to do me when created under a different user account than the one I'm trying to create content for? (i.e. 1) work, 2) ArcGIS Personal).
Basically, what is the correct method? How do I get an API Key so I can follow the tutorials and programmatically generate content in my main, paid-for, licensed Portals?
And PLEASE, fix the tutorial so it tracks with reality!