I don’t think I’ve ever seen a CNC router used to cut corner bevels like that. Unless you’re doing some really funky geometry, I’d use the CNC to cuts the parts to size and shape, then cut the bevels with a table saw.
The table saw would be the best way to go. You can do a 3D type cut but it will be slow and not truly a good angle cut for your purpose, the other way to do it is find a bit with the angle on it you want, and use that to contour the edge you need.
When you have injection molds (most any mold really) made all the cuts are done with a 2-5 degree taper bit. This leaves you with a angled wall to make part release easy.