Arduino IDE1.8.10

I am unable to install new boards. I added the following URL to preferences:

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.

What board are you trying to install.

The ADAFRUIT is not a specific ARDUINO brand as such.

Might I suggest you READ THIS and add any additional information.