The Mu editor works really well with the Metro M4 Express AirLift and it is the recommended choice for editing CircuitPython code.
This project was set up and tested using CircuitPython version 5 or higher. You will want to update your Metro M4 Express AirLift and Libraries to match the version you are using.
Next you'll need to install the necessary libraries to use the hardware carefully follow the steps to find and install these libraries from Adafruit's CircuitPython library bundle matching your version of CircuitPython. This project uses CircuitPython version 5 or later.
CircuitPython Library files used in this tutorial
Plug your Metro M4 Express AirLift into your computer via a known, good USB data + power cable (not the kind that comes with USB battery packs, those are power only). A new flash drive should show up in your computer's file explorer/finder named CIRCUITPY. If it's not there, check your cable and that you installed CircuitPython correctly earlier.
The following libraries are used here. Copy the corresponding file from the library bundle to your CIRCUITPY drive in a subdirectory named lib. Create this subdirectory, if necessary, then copy these files/directories:
Before continuing make sure your board's lib folder has the following files and folders copied over. Note that the non-library files will be retrieved in the page called "The Full Code".