I wasn't expecting the first reason that I explained above to be the culprit, but surprisingly it is! By the looks of your folder, there is no .material file, which is necessary for a preset to show up in-game. .Material files are filled with "coding" that "tells" the texture how to appear on the model in-game. Without that file, the game will glitch, rendering the game to not have that preset as an option. Since it seems the download did not come with a .material file, would you like me to find and/or make on specifically for that preset?
No need to apologize for asking questions! We're here to help you, and if you ever have anymore questions, as I said previously, do not hesitate to ask.