Add custom emmet snippets to Textastic on iOS

I'd like to add some custom Emmet snippets to Textastic on iOS, but I can't make it work.

I tried following the directions on Emmet's site for adding the file (https://docs.emmet.io/customization/snippets/), but I'm not sure where to put it. I've added the snippets.json file to #Textastic, but it won't take.

Is it possible to use this file right now? Does it need to go in a subfolder of #Textastic?