Adding Hybrid Connect form into Category Description is possible.
For this you need to install a free plugin named "Widget Shortcode" http://wordpress.org/extend/plugins/widget-shortcode/ .
This plugin Outputs a widget using a simple shortcode.
Example shortcode generated by Widget Shortcode plugin :-
Go to your widget area & copy the shortcode generated by Widget Shortcode.
Now you can put this Short code into category Description field.
If it doesnt work, Please feel free to contact technical support & mention this solution in your ticket.