Mu is an editor for embedded projects (Mu development is currently in alpha). Mu will work as a serial terminal to the SAM32, but we first need to add our board to the list of accepted CircuitPython projects.
/Applications/mu-editor.app/Contents/Resources/app/mu/modes)/circuitpython.py file in a text editor and add (0x04D8, None), to the the valid_boards list (somewhere around line 54) and save. The file should now contain something like:...
  (0x1B4F, 0x8D22),  # SparkFun SAMD21 Mini Breakout
  (0x1B4F, 0x8D23),  # SparkFun SAMD21 Dev Breakout
  (0x04D8, None),    # All Stanford-related Boards
]
Follow the same steps as for the mac, except the adafruit.py file will be located in a directory similar to...
C:\\Users\\USERNAME\\AppData\\Local\\Mu\\\\pkgs\\\\mu\\\\modes
(make sure to change 'USERNAME').
circuitpython.py file?