Open Source Document Management System | OpenKM

Hello everyone
I am just trying to explore "categories" concept but public demo instance of OKM is givving me "Error when communicationg with server (GetChilds)" error when trying to display categories.
I have also tried on mine downloaded community instance version 6.3.2 (build: 8289) where I have no error returned but I can only create a folder under categories but all other options to create/delete are grayed out.

Can you please advice how to manage this categories?

Thanks!

In the catalina.log file ( into logs folders ) should be shown the complete stack trace error. I would like starting with it. Please share the log error section here.