Machining isn't printing, you need to have some I put into how you want the job to work,

Printing you build up microns at a time, it takes hours and isn't strong enough to last an hour, machining takes .125" cuts manufactures the parts in minutes and they last for decades,

CAMWorks has some of the most advanced afr of any cam system, but even after afr you as the machinist will need to make some choices, leadin, out, depths of cut, cutters to use etc, I really think you should invest some time and some money in some good quality training. Especially if you are new to manufacturing,

If you just wish to do that tab all you would need to do is use a corner slot.