Working on non-mobile version

I have this plugin installed at http://preachnet.com/freeindeed/

The plugin is working, but it is present on non-mobile devices. I assumed it would only show up on mobile, but it’s showing up on all screens.

Am I wrong in assuming this plugin would only show the add to home screen feature on mobile? Is this plugin supposed to be installed on a mobile only site (and not a responsive site)? Or is there a setting I’m missing somewhere to make it only show up on mobile?