first you gotta convert the aiff file to mp3 format by any of the coverters online
then you gotta open it in autdacity, which is available for both windows and linux.
zoom in and then you will see that short blips have less frequency and they are . ( morse dot)
the high frequency portions are - ( morse dash)
put that on any of the online morse to text converters and you'll get the flag. don't forget the spaces.