Many Android phones and tablets have their SC Cards formatted in FAT16 or similar. This creates a technical limitation not allowing files bigger than 2GB to be saved to the FAT16 SD Card and bigger than 4GB to a FAT32 formatted SD Card.
You can read more about it on Wikipedia.
FrostWire won't download any file that’s more than 2GB to an Android where the memory has a format FAT16 or similar because the system won't allow it to properly save that file.
When you try to download a file that's bigger than 2GB to a FAT16 formatted SD Card or 4GB to a FAT32 formatted card and FrostWire can't save it, it will give you just an Error message or might say "error: setLength fails, truncate failed: EINVAL" or similar.