/etc/postgresql/13/main/pg_hba.conf

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

/etc/postgresql/13/main/postgresql.conf

listen_addresses = '*'

systemctl restart postgresql

apt install libpq-dev python3-dev gcc
pip install psycopg2

sudo -u postgres psql
...
\q

ALTER USER postgres PASSWORD 'myPassword';

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