WebHDFS not working on a secure hadoop cluster
Looks like you do not access WebHDFS (default port = 50070) but HttpFS (default port = 14000), which is a "plain" webapp that is not secured the same way.
A WebHDFS url is often something like http://namenode:50070/webhdfs/v1 ; try to modify hue.ini with that parameter (WebHDFS is recommended over HttpFS)