Again, there is not ONE magic command that is going to work on the TWO different boards you have, EACH board requires its own special command.
I've told you how to do it:
On the ZUMSpot board use:
sudo pistar-zumspotflash rpi
On the board by Florian use:
sudo pistar-mmdvmhshatflash hs_hat
Don't use the incorrect command on the wrong board.
You shouldn't have to compile the firmware. What I think is going on is you are either installing the wrong firmware, and it is having trouble communicating with the modem, or the problem you have is not anything to do with the firmware, it is somewhere else in the configuration, and you are trying to fix something that isn't broken.
You haven't said what the problem you are experiencing is, only that "it doesn't work". That doesn't help anyone figure where to begin to try to help you. What doesn't work, do you get an error flashing the modem when running that command? What does the log say?