Create a python3 virtualenv:
virtualenv -p python3 _env

source _env/bin/activate
pip3 install -r requirements.txt

Install postgres:
sudo apt-get install postgresql

Connect to server as user `postgres`:
sudo -u postgres psql postgres

Change password for user `postgres`:
\password postgres

Set up database:
CREATE DATABASE cat_9;
CREATE USER cat_9 WITH PASSWORD '<some_password>';
GRANT ALL PRIVILEGES ON DATABASE cat_9 TO cat_9;

Find which port postgres is running on:
SELECT name, setting FROM pg_settings WHERE name = 'port';