@Korodny: I don't think your problem comes from the file type. If there is nothing at screen (no error or success message) when you click on "Upload your file", then the problem is on your side...
I'm using standard form in order to upload the files in the zone, does your actual browser support them correctly ?
I don't think I can do more for compatibility on my side, try to use another Amiga web brower
@anyone which can upload files into the zone with one Amiga web browser: which one please ?