If your user has all necessary permissions for the nginx server and you filled in the nginx config file with correct data but still get 403 error, check the sites-enabled folder. If its empty, you need to create a link using the command:

sudo ln -s /etc/nginx/sites-available/your_site_conf.conf /etc/nginx/sites-enabled/

and then restart sudo systemctl restart nginx.service now nginx understand that your site is enabled. One day I got stack on this issue, cuz I just skipped step when i should have created this link.