Pixelmon Mod

I've been wanting to upload some schematics I have for arenas and town buildings I have, however, I can't figure out how to get Sketchfab to work for Mac. Unfortunately, it requires Terminal coding that I can't get to work. I can't find any tutorials anywhere, and the official site only tells you what to download and not how to set it up. If I can get any help, or if there is an alternative. Please let me know.