It won't directly control a CNC machine. You need a piece of software that will translate the AutoCAD models into G-code that the machine controller can execute. VisualMill is a relatively inexpensive program that does this; I sell it for $800.
Finding a CNC router with the capacity to do your 24" globes will be a challenge, especially for the budget you state. Even assuming that you're doing these molds as halves, you'll need enough height in the Z axis to allow your tool to clear the high edge, so even if you can do this with a 3" tool and assuming the mold is 1" thick, that comes to 16", which is considerably higher than most routers' stock configurations. Your best bet might be to find a company willing to build you a custom machine.
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