A standard text editor is all that's necessary to program the SAM32. However, beginners should install the Mu Editor to make the REPL more easily accessible. For advanced users, see Accessing the Serial Console if you don't want to install Mu.
Download Mu: https://codewith.mu/en/download (release or latest alpha version work)
Now you must fix Mu → Configuring Mu Editor to Work with the SAM32
Confirm Mu is set up properly by starting Mu and selecting "CircuitPython" when prompted for the mode (as shown)
Plug your SAM32 into the computer via the micro USB port and select the "Serial" button along the top bar. You should now see something similar to the image below. If you get an error, ensure you followed step #2 above.
Click inside the "CircuitPython" REPL box and press CTRL + C
on your keyboard. You should now see something similar to...
🎉 congratulations! Mu is now successfully installed and configured.