bootable usb not working not 2010 mac

My macBook 2010 uni-book white never seems to find a bootable USB, but it finds a cloudready USB. is it possible to change iso to BIN so chromebook recovery utility can use it. i did try dd but it does nothing. Is there any way to do this with cloudready OS. edit: i use dd to make the usb bootable, like this sudo mkfs.ext4 /dev/sdb on crosh, not linux on cloudready OS