As for now I was using such kind of snippet:
Local $aFTP_FileList = _FTP_ListToArray($hFTPSession, 2)
For $iFTPFileSize_idx = 1 To $aFTP_FileList[0]
ConsoleWrite('Pobieram informacje o pliku:' & $aFTP_FileList[$iFTPFileSize_idx] )
$iWielkoscPliku = _FTP_FileGetSize($hFTPSession, $aFTP_FileList...