Set up a postgres database with a specific role without password prompt
You edited away the problem.

In your comments you say that the database is really projATX_db. At least that is what you think. But PostgreSQL translated all unquoted text to lower case, so when you run

CREATE DATABASE projATX_db;


the database is really called projatx_db

Now the entries in the password file are not subject to this lower case conversion (that is specific to SQL), so projATX_db in the password file does not match your database.