Select MariaDB and a version. And I chose free tier.
Enter basic information as you want.
DB instance identifier is not database name inside DB. I will enter database name below. A username and password will be used when I connect to the DB.
I created new security group for this DB.
I chose a specific AZ where the EC2 will be. If they reside in different AZ, it will cost network transfer fee between AZ.
I entered initial databse name which will be used to connect DB.
I chose the custom DB parameter group that I made in previous step.
Though I chose free tier, it still shows estimated price. But the free tier will be applied if the condition is met.