This is a quick summary of the official guide on how to install CircuitPython on a MagTag .

Load with UF2 Bootloader

This is the easiest option. If your MagTag has a black front it came with UF2 installed.

1. Download the latest CircuitPython release
2. Attach your MagTag to a computer
3. Launch UF2 by double-clicking the Reset button (might take a few tries)
4. If UF2 is installed you will see a new disk drive appear, called MAGTAGBOOT
5. Copy the UF2 file onto the MAGTAGBOOT drive

Your MagTag should auto-reset into CircuitPython , or you may need to press reset. A CIRCUITPY drive will appear. You did it!

Load with esptool

If you have an original MagTag (white front) you need to use esptool. Check the official guide for instructions.