Can't activate collapsing categories widget

I have installed the collapsing categories plugin and I have added the widget to my Woocommerce sidebar. The sidebar has a custom menu in it which displays my categories. http://test.pommedorange.com/
I would like to have these categories collapse/fold.
However, after searching the internet on how to install or activate this widget I still have not managed to make it work.
Any help on this is much appreciated.

https://wordpress.org/plugins/collapsing-categories/