After installed WordPress (https://www.teachonetofish.net/set-up-wordpress-on-single-instance-ec2-in-ubuntu/), you need to do the initial setup in WordPress.
Setup WordPress
Assume you installed the webroot/wordpress folder. Then in your browser, open URL
http://your-ip-address/wordpress/
Choose your default admin page language.

Setup your admin user and password.
All done!
WordPress Admin page
http://your-ip-address/wordpress/wp-admin