Arduino Nano 33 BLE - How to make it visible as USB device on MacOS?

How do I get this Arduino Nano 33 BLE Sense board to show up as a USB storage device on MacOS? I want to use CircuitPython. The directions (below) say to "install the appropriate UF2 Bootloader"
on the board by uploading a special .ino sketch but there is no such sketch available for the Nano 33 BLE. Is there another way to get CircuitPython setup on the Nano 33 BLE. (Note: the mac and the Arduino IDE recognize the Nano 33 BLE fine. I can upload sketches OK. I"m stuck trying to get the UF2 bootloader onto the board! Thanks!

The Nano 33 BLE doesn't have a SAMD21 microcontroller, so that is definitely the wrong guide. It has an nRF52840 microcontroller.

I think you'll find all the information here:

and at the link from that page.