You have found database credentials in config file. Let use mysql client to connect and dump the database.

mysql --host=HOST -u USER -p
--host xx : Server IP or name
-u xx     : login
-p        : manually enter the password.

List databases.

show databases; 

Ignore internal databases and choose the application database.
The database 'information_schema' contains internal information of mysql or mariadb. It can generally be ignored.
Select the aplication database, list tables, then dump interresting tables such as 'users'.

use DATABASE;
show tables;     
SELECT * FROM TABLENAME;