Plugin Not Working With GridStack Theme

Hi,

I tried a gallery on a site with the Gridstack theme, with and without the plugin activated and it looks the same, and there are no controls.
https://medium.eplatt.com/test-gallery/
Is the built-in gallery overriding it? How do I de-activate the built-in one?

Thanks!

https://www.ads-software.com/plugins/photospace-responsive/