I'm trying to create a bootable installer as per instructions, but terminal says: ...createinstallmedia: command not found What could be the reason and do I fix it?

Hello, I'm trying to create a bootable USB drive and trying to do it in Terminal according to the Apple instructions:

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

(With replacing MyVolume with the name of the USB drive). 


Terminal says: 
sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia: command not found

 
How can I fix it? Is there any other ways to do it?

Thanks you.