Problem with model loading

I'm altering the data pack https://modrinth.com/datapack/plushie-friends (not mine) in ver 1.21.8 . I am trying to add another plush with this datapack (it gives bundles a model), but whenever I use a command to give me the item, I get a item with a placeholder model and texture. I have tried troubleshooting for an hour or so and I cannot get it to work.