CREATE USER X IDENTIFIED BY PASSWORD
Googled that and not one result on the first page mentioned PostgreSQL. I don't think this approach is a common one at all. More to the point, I'm not sure i've ever seen that set of instructions anywhere, ever, for pgsql. Every tutorial and intro focuses on running 'createuser'.
Oh, yeah, and you'll need to be root to go in and futz with your pg_hba.conf file, then have permissions to write it out and restart the server (probably as root).
This 'createuser' approach hasn't been a '5 minute experience' - it's been the approach that is promoted as the default answer/approach almost everywhere I've ever looked for several years.
`su postgres` or whatever user it uses;
run `psql`;
`CREATE USER X IDENTIFIED BY PASSWORD;`
`CREATE DATABASE X OWNER X;'
Now X can connect there and add tables as he wishes.
Postgres onboarding coule be better, but it is naive to choose a tool you will use for years based on the first 5 minutes experience.