The Easy Way: our install script for bench will install all dependencies (e.g. MariaDB). See https://github.com/frappe/bench for more details.
New passwords will be created for the ERPNext "Administrator" user, the MariaDB root user, and the frappe user (the script displays the passwords and saves them to ~/frappe_passwords.txt).
GNU/General Public License (see license.txt)
The ERPNext code is licensed as GNU General Public License (v3) and the Documentation is licensed as Creative Commons (CC-BY-SA-3.0) and the copyright is owned by Frappe Technologies Pvt Ltd (Frappe) and Contributors.