The zip contains the JSON workflow but the image in "sample files" should also contain the info. So you should be able to drag and drop that into comfy. The example image will do nothing. It's just to show you how well it works.

I set this to work with epic realism 1.5 but it should work with whatever realistic model you want to use. You will just need to configure all the k samplers and possibly the Tgate.
Make sure you have Comfy Manager installed and just tell it to install any nodes you are missing and everything should work fine after a restart. Just drop an image into the load image node and hit queue prompt. Thats it.
If you have any questions feel free to hmu.