postgresql Cannot login with created users
It's just a case folding problem. You're trying to connect with myUser but due to case folding rules, you created myuser in lowercase, as the \du output shows. Per documentation:


  Quoting an identifier also makes it case-sensitive, whereas unquoted
  names are always folded to lower case.


To create myUser with this exact case, enclose it in double quotes, as in:

CREATE USER "myUser" WITH SUPERUSER PASSWORD 'password';


Then the invocation psql -U myUser ... will work.

Or alternatively, don't recreate the user but always refer to it in lowercase.