Not Working in Catchbox

I am trying to get this plugin to work with the Catchbox theme. It appears to work fine when using the resize feature on a monitor. However it does not work with an Iphone. I give a weird result no accordion of the menu titles and the output is not in the order of the original menu.

my site is http://www.derbysbest.org

I would appreciate any help you can provide.

https://wordpress.org/plugins/slicknav-mobile-menu/