Copying this package over USB will not work anyway, even if you get all the dependencies, since firmware-b43-installer is just a script that downloads the firmware (probably because it is illegal for Debian/Ubuntu to redistribute this firmware because of the license).
You need internet. You’ll need to use a different network device for this, or use a phone as the other person said.
Or you can copy the firmware files over by hand, from a different Ubuntu/Linux computer. They should be under /usr/lib/firmware/b43.