Hello Amanda,
First of all, you do not need third party plugin to use retina images. You simply just need to upload images with @2x suffix which are twice the size in dimensions of the original image. So, for example, you have an image named abc.jpg which is 400x800 then you just add the second image which is 800x1600 and name this on abc@2x.jpg
Additionally, looking at the console on page link you provided above, I see there is an error with following: https://img1.wsimg.com/tcc/tcc_l.combined.1.0.6.min.js.map
I suppose this is coming from the plugin - so, try removing the plugin and upload your images. Once uploaded, you will need to Regenerate thumbnails by going to Tools >> Regenerate thumbnails and the new retina images will show.
Please let me know if you still need help with this after you have done above steps.
Thank you