Hey Bruce,
Blender is good for creating and modeling 3D objects.
FreeCAD is a all-in-one-solution that can do everything. You can create a 3D model (or import one), and then make a g-code toolpath of it and export it to the Onefinity CNC and directly mill it on your workpiece.
I assumed you wanted to try the free and open source software first, before you pay $699 for Vectric Pro. Many people use FreeCAD and are very happy with it.
It offers vast documentation and tutorials: