If you have your own server, the first thing you may want to do with your backend shoud be to install a database server on it.

Here is step by step how to install a MySQL/MariaDB (almost the same) database on your server:
Install the MariaDB service:

yum install mariadb mariadb-server

Create your user access – change the username and password you want:

mysql
CREATE USER username@'%' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON *.* TO 'username'@'%' ;
flush privileges;

Verify the user has been created:

SELECT User FROM mysql.user;

You should be able to login on your database from you app and remotely.