Before flashing, make sure you have enabled "OEM unlock" from "Developer Settings" !
Note that CFAR's display code isn't yet compatible with the S7, as such, there is no output on screen. This means that after flashing with ODIN, the device will only show you the S7 logo, and it seems like nothing happens. Just leave the device alone for 5 minutes. It'll reboot a few times, then boot into Android, but now you have root.
If it still doesn't do anything after 5 minutes, something has gone wrong, and you should probably reflash your stock boot.img and recovery.img.