title: FATAL: password authentication failed for user "postgres" (postgresql 11 with pgAdmin 4)
body: <p>I recently installed Postgresql 11, during the installation, there's no step to put password and username for Postgres. Now in pgAdmin 4, I wanted to connect the database to server and it's asking me to input password, and I haven't put any in the first place. 
  Any one knows what's going on. Thank you!</p>