Use the odoo-install.sh script to install
sudo chmod +x odoo-install.sh
./odoo-install.sh1- Open Terminal and enter => sudo su postgres
2- Enter password for postgres System user (if it is necessary)
3- createuser root -s
4- psql template1
5- alter role root with password 'yourpassword';
6- \q
7- exit
source: https://www.odoo.com/forum/help-1/question/operationalerror-fatal-role-root-does-not-exist-123992
cd /path/to/odoo13
pip3 install setuptools wheel
pip3 install -U -r requirements.txt
sudo service postgresql restart
python3 odoo-bin --addons-path=addons