create user, and then database for that user.

  sudo -u postgres psql
  postgres=# create database mydb;
  postgres=# create user myuser with encrypted password 'mypass';
  postgres=# grant all privileges on database mydb to myuser;
  

https://stackoverflow.com/a/75876944/1173856

to enable logins from external systems: 
  find / -name "postgresql.conf"

find in there ''listen_addresses = 'localhost''', change to ''listen_addresses = '*'''

pga_hba.conf is probably right next to it. add these:

  host    all             all              0.0.0.0/0                       md5
  host    all             all              ::/0                            md5