How to configure a Postgres DB at AWS?

Hi guys

I read like described the blog post how to set up an app at AWS with the Mendix software subscription, but dont get how to configure a (new) postgres database?

When trying to start the app at the server I got this

m2ee(admin): start
INFO: Trying to start the MxRuntime...
Database password not configured, please provide now:
ERROR: Executing start did not succeed: result: 1, message: DatabaseType has no value
INFO: Waiting for the application to shutdown...
INFO: The application has been stopped successfully.
m2ee(admin):

I read that the image has also a Postgres db, but wondering where this db is, what the dbname and passwords are?

Anyone more info about this stuff