Add the following to Additional Boards Manager URLs

https://adafruit.github.io/arduino-board-index/package_adafruit_index.json

In the board manager search for Adafruit SAMD Boards and install it.

Copy libraries into your library directory.

Set board to Adafruit Feather M0.

Current measurements: Running: 22mA avg Sleep: 1mA !! :( So there's 0.5mA going into the sck pin of the serial flash. Try setting the SCK pin to an input when we're asleep? Or setting it to low voltage when asleep?