Ape Apps

How do I make texture mods? I don't see the "create texture mod" button on Mac (downloaded from the App Store) or PC (downloaded from Microsoft Store or directly from Ape Market) so I tried making a test mct file manually by encoding my image with base64 and using another mct as a template, but the game crashes every time I try to import it. How can I solve this? I don't mind making the mct manually if I have to, as I have plenty of json experience, but I'd like to know what's causing all of the crashing. I've attached the sample here.