I am unable to install new boards. I added the following URL to preferences: https://adafruit.github.io/arduino-board-index/package_adafruit_index.json
I then went to boards manager to install arduino SAMD boards. none appear nor do any of the Adafruit SAMD boards.
I even did a complete uninstall (including ...AppData\Local\Arduino15 and ...\Documents\Arduino) and reinstall. Nothing works. I need to move along, any help would be welcome.
I have a windows 10 machine (Intel Skull canyon) and am using Arduino 1.8.10.