Android 7.1 upgrade to Ubuntu using SD card

While following the instruction here : http://wiki.t-firefly.com/en/Firefly-RK3399/ubuntu_support.html#android-7-1-upgrade-to-ubuntu, I am trying to unpack the image. But when I run unpack.sh, I see the following error :

start to unpack update.img…
./unpack.sh: line 17: ./bin/rkImageMaker: No such file or directory
Press any key to quit:

The file is there :
$ ls -l ./bin/rkImageMaker
-rwxr-xr-x 1 nhjadhav domain^users 325822 Nov 12 16:54 ./bin/rkImageMaker

Is there anything else that is needed to be done to unpack the image?

I had unpacked FIREFLY-RK3399-UBUNTU18.04-GPT-20190910-0922.img by following the instruction of wiki just now, and it was no problem for me. Therefore:

  1. Please make sure ubuntu_sd_update/bin/rkImageMaker exists.
  2. Re-download the ubuntu_sd_update.zip and try again.
  3. Please try to execute the commands in the command line instead of running ./unpackage.