error message please help

Arduino: 1.8.12 (Mac OS X), Board: “Adafruit Gemma M0, Arduino, Off”

/Users/mattwilliamson/Documents/Arduino/libraries/Adafruit_Flora_Pixel_Library/Adafruit_FloraPixel.cpp:2:10: fatal error: util/delay.h: No such file or directory
#include <util/delay.h>
^~~~~~~~~~~~~~
compilation terminated.
exit status 1
Error compiling for board Adafruit Gemma M0.
Invalid library found in /Users/mattwilliamson/Documents/Arduino/libraries/Nebulophone: no headers files (.h) found in /Users/mattwilliamson/Documents/Arduino/libraries/Nebulophone
Invalid library found in /Users/mattwilliamson/Documents/Arduino/libraries/Nebulophone: no headers files (.h) found in /Users/mattwilliamson/Documents/Arduino/libraries/Nebulophone

This report would have more information with
“Show verbose output during compilation”
option enabled in File → Preferences.

I have a very strong suspicion that the Adafruit_Flora_Pixel_Library library was written with AVR microcontrollers in mind, not a M0.

From the library's readme:

This library has been deprecated and fully replaced with GitHub - adafruit/Adafruit_NeoPixel: Arduino library for controlling single-wire LED pixels (NeoPixel, WS2812, etc.)

I'm certain the Adafruit NeoPixel library will support your Gemma M0.