Can't connect psql on macOS Install

$ brew install postgresql
Updating Homebrew...
==&gt; Downloading https://homebrew.bintray.com/bottles/postgresql-12.1.mojave.bottle.tar.gz
Already downloaded: /Users/user/Library/Caches/Homebrew/downloads/525a3637cd6f7b7a7e0bfe5adb102483ae01f4be31269aaf4348f6f4291f8a86--postgresql-12.1.mojave.bottle.tar.gz
==&gt; Pouring postgresql-12.1.mojave.bottle.tar.gz
==&gt; /usr/local/Cellar/postgresql/12.1/bin/initdb --locale=C -E UTF-8 /usr/local/var/postgres
==&gt; Caveats
To migrate existing data from a previous major version of PostgreSQL run:
  brew postgresql-upgrade-database

To have launchd start postgresql now and restart at login:
  brew services start postgresql
Or, if you don't want/need a background service you can just run:
  pg_ctl -D /usr/local/var/postgres start
==&gt; Summary
  /usr/local/Cellar/postgresql/12.1: 3,217 files, 37.3MB


Check status

$ brew services list
postgresql     started user /Users/user/Library/LaunchAgents/homebrew.mxcl.postgresql.plist


Connecgt

$ psql
psql: error: could not connect to server: FATAL:  database "user" does not exist


$ psql -U postgres
psql: error: could not connect to server: FATAL:  database "postgres" does not exist


It already inited database, why postgres does not exist?
This guide works very well:

https://gist.github.com/ibraheem4/ce5ccd3e4d7a65589ce84f2a3b7c23a3

It's necessary to create db and role manually since they aren't exist.