FYI
Installing to a named instance requires the following:
Not only to you neet to make sure that TCP/IP connections are enabled for the instance using SQL Server Configuration Manager, but you also need to specify the port.
From the SQL Configuration Manager:
Protocols for NAMED_INSTANCE -> TCP/IP -> IP Address Tab
Scroll to the bottom and under IPALL change the TCP Port to 1433 (default SQL)
Restart the SQL Service and go back to the SSO installer
JDBC URL:
jdbc:sqlserver://<SERVERNAME>:1433;instanceName=<INSTANCE>;integratedSecurity=true;databaseName=RSA
Cheers.