Connecting to Postgres Amazon RDS using IAM authentication

Hi all, I am trying to set us IAM authentication to connect to my Postgres RDS 14.2 instance. I am following https://aws.amazon.com/premiumsupport/knowledge-center/rds-postgresql-connect-using-iam/ to set things up. I can connect to the instance using the authentication token without performing any of the IAM tasks which are mentioned in the document. The following are the steps I followed.

1. Create a Postgres 14.2 instance

2. Enable IAM authentication on the instance

3. Login to my instance and create a DB user with login and grant rds_iam to the user.

4. Generate the authentication token for the user.

5. Login to the instance with the generated authentication token.

   I was able to login to the instance without any issue. If you notice the above steps I did not create an IAM user nor have I created or attached any policy as mentioned in the documentation. Am I missing something? I don't this that is how it is expected to work.

Thanks, Kris