To all out there who are new like me and are looking for a solid FREE software setup.
After trying Estlcam which apparently worked straight and well, I was looking for a completely FREE software solution for my Windows10 - Arduino Uno - Uno CNC V3.0 Shield system.
The combination of grbl & UGS (Universal G-Code Sender) & Freecad works great for me so far. These are the steps:
Step 1: upload grbl to Arduino (Arduino Uno in my project)
https://arduinoboardproject.com/en/how-to-install-grbl-on-arduino-uno-with-the-arduino-ide-software/
Step 2: Install UGS at your computer. All info here:
*With these two above you should be able to control your MPCNC
Step 3: Download freecad to generate gcode. It is a great program, it has taken me a couple of days to learn the basics and draw basic contours with my MPCNC. There are countless tutorials on youtube.
It took me a week to figure all these out, so I hope this will save you time.