You want to install the APM Database (Postgres) using the silent install method.
Set the Postgres user to be the same as user that will be doing this install.
The default for the Postgres user is "postgres", if you are logged in as "APMAdmin" then, you will need to include your login credentials in the new response file.
This issue was found in APM 10.5 but could be found in other releases.
In the response files, you will need to replace the Postgres user with the logged in user that will be running the silent install.