Not to worry @PoulpeInvisible, I'm sure we can figure it out!
From the lack of texture and animation, it sounds like it might be a path related issue in one of several places, so I'll just go over an example of how I have things structured for my own TimeFrame animations:
To start with, I like to make sure everything is in a nice folder structure that I can simply ZIP it at the end and upload. Typically it looks something like this:
Each of my OBJ files is set to use the same material (doesn't really make a difference, but neater since they all use the same palette), and the texture file is located inside the texture folder. Make sure the MTL file reflects this pathing like so :
OBJ files are also text readable, so it's worth checking they have the correct pathing to your MTL file. You can open them in any text editor. Using the file structure I've shown you should see something like this near the top of the file:
Last but not least, we have the TimeFrame file itself. This is where the animation magic happens. For the simple walk cycle that makes up my example (it cycles the frames twice) the timeframe reads like so:
Make sure that the naming is correct ("sketchfab.timeframe") or it won't get processed to make the animation.
Hopefully something here helps - there are a few places that pathing can trip you up. But if not, feel free to share the files you're uploading and I'll take a look