The most common oversight in configuring the RDS server is failing to enable the RDS servlet in web.xml.
Go to the default folder C:\lcds\tomcat\webapps\lcds-samples\WEB-INF and open web.xml in a text editor. By default the RDS servlet is commented out, locate the comment tags <!—begin rds and end rds--> and either remove them or adjust the comment syntax accordingly.
Additionally, you have included authentication in the RDS configuration. Is the role and user 'admin' defined to Tomcat?
Steve