On the macOS computer, download the ISO file
- open a terminal
- run the diskutil list command
- find the name of the USB key (in my example /dev/disk4)
- run the command sudo diskutil unmountDisk /dev/disk4
- run the command sudo dd if=pathoftheISOfile of=/dev/disk4 bs=1m
- wait for the action to be finished and remove the device from the computer