setting receiver-type to beast seems to be only supported for the sd-card image.
So i have added the flightaware repository to my debian sources, did you do the same?
If so you might be able to just do an “apt-get install beast-splitter”. (i’m running on an rasperry though and the package might not be available for regular pcs.)
if you are not running a raspi you might need to just compile it from source.
running dpkg-buildpackage as stated in the readme on github will probably result in errors until you install quite a few dependencies you need to compile stuff. a bit of a hassle but just give it a try 