trying to set up a IDP for localhost testing

[Cantor, Scott]

Using localhost is a bad idea and you will tie yourself in knots trying to make it work because that's artificial and doesn't match any real world scenario the documentation is focused on.

> Is there somewhere a simple step by step guide to get this
> working? I’m not even succeeding in getting the Hello World > module running.

It takes hundreds of hours to produce that material, and making it "better" takes hundreds more.

The IPAddress login flow or the  htaccess support in the Password login flow (mentioned by Fabian) are the "simplest" back-ends for authentication.

There is no obvious way to get a result like you're describing, so I have no means of guessing how you managed it. 

> (the documentation often seems to say I need to do X or Y,
> but then doesn’t go on to explain how I need to do X or Y),

Find me one and I'll add a note to improve it. Anything like that should be a link to the relevant part of the documentation unless it's simply presumed knowledge,.

-- Scott