Another things that I learned (and may have relevance) is that the drupal database is also used for the postgis database, the user needs to be enabled and I believe needs to have the same credentials as the drupal user.
To further complicate things geo server needs the same default id and login as postgres admin.if postgres was installed using stack installer.
The last was more of an issue if installed with postgres stack installer on windows ( perhaps linux as well ) as it sets up the admin account in advance of cartaro ) cause you will install that next ).
The stack installer will make a drupal database and user. Cartaro looks for postgres admin, however, if that is different form the drupal user set up by postgres stack installer.
There are a lot of different ways this could be handled but it is trial and error with a lack of current documentation or much user experience to guide you.
I'm guessing linux is the way to go here currently ( and perhaps, no stack installer )