I am using the AMI that Jaspersoft has in the AWS marketplace.
As I explained in my first post - I can connect to the database (the test user has Administrative privileges), I can see all of the Schemas, I can test the connection, but cannot create a Domain.
Just to confirm that the JasperReports Server is working, I created a Database in Redshift, connected the JasperReports server to it and created several Domains and Reports.