Hey,
this little thread that might help you understant why your submission might be declined. I had a hard time finding a way to post my product since always after submiting, it was automaticly declined with no notification and no reason. After contacting Epic, find ou it was because I used ZIP to pack all my files. I was using WinRAR to convert to ZIP, there are 2 types of ZIP files, the normal ZIP files, and ZIP64, they have the same .zip extension, and basicly ZIP64 enable the possibility to do more than 4Gb per files. But FAB does not support ZIP64 and WinRAR seems to convert automaticaly to ZIP64 even if it’s lower 4Gb. The way I found to be sure I wasnt exporting ZIP64, is to use 7zip, and you’ll find if it is zip64 in the info panel.
Also, to FAB’s devs, it is not clear that zip64 isn’t supported as it is not talked about on the supported file formats.