You should be able to import 5-axis 3D printing tool path by simply drag and dropping the NC file in RoboDK.
But RoboDK can't help you create such a file.
You need to find a slicer that can do such a thing and I don't know any personally.
This is what I am studying for my Masters's Thesis currently. Hopefully, I can share my finalized thesis mid 2022 with you then. But obviously, this won't help you now. I am currently using rhino and grasshopper to create tool paths. Still waiting on a response from the team at RoboDK on IO control for my robot so I can test simulations without manually turning on and off my extruder at layer changes. Hopefully either I can get some guidance to point me in the right direction or once my classes finish I can devote more time to trying to figure it out.