We had a Flow waterjet at work, and I believe their software is the only s/w that will work with their machines. I assume their controlers are all based the same. We had a Bengal. You could not use g code.
I will be the first to say, Flowpath and Flowcut suck. It was just replaced with an Omax. It is an awsome machine and their software is free (with purchase of the machine). No fee for upgrades or new versions like Flow. And as many copies as you want to run. They told us to install it at home if we wanted.