Restoring a desktop CNC

I have a MaxNC which doesn't work.  Last time it failed I went to the seller and their repairs cost a lot and did not last.  Even simply doing precision drilling on some grade 8 bolts for my brother ended in none of the motors working.  Since factory repair costs too much I've gathered home repair parts to completely replace factory electric hardware and hopefully the software. But I don't know what to do with the software to get it up and running in spite of seeing many YouTube videos that address the subject but not in enough detail.

Does anyone know how to set up and run an Arduino with CNC shield hooked up to 4 wire steppers?  Is that under Windows or Linux?  I want to set it up on two computers, a Windows running Fusion 360 (which is free for hobbyists) and generate G-codes. Then transport them to my garage to run on a Raspberry Pi to run the CNC machine. The Fusion 360 works.  One problem is i don't understand Linux enough.  So when I saw online instructions saying I need to flash the Arduino, I had to ask what that meant.  When I found out it was sending an Arduino binary to the Arduino board, I don't know how to ask Linux to do that, or any of the other steps needed to run a file of G-codes.

So, how do I proceed?  Thank you.