I see the same question was asked before (4 years ago), but it was unanswered.
Today, I am getting the same issue.
Using Embedded PostgreSQL DB, I enter what I want for DB name, usernames etc. Click create & I get "Connection refused: connect"
If I click Next, I get a slightly different response: "Unable to establish connection: Connection refused: connect"
WHD v12.7.11 (clean install today)
Windows10 Pro x64 (clean install today)
Windows firewall off
Any help, suggestions will be much appreciated
Regards, Ralph