Arduino IDE 1.8.14 , 1.8.15 doesn't handle ItsyBitsy

There seems to be no forum to discuss IDE versions prior to 2.0 beta....

I installed Arduino IDE 1.8.15 and wanted to allow use of the ItsyBitsy board, but the Board Manager in the IDE doesn't include it. When I first bring up the Boards Manager it shows:

When I type "Itsy" or "ItsyBitsy" or "ItsyBitsy 32u4" NOTHING comes up in the options.

No matter what I try in tat Boards Manager dialog it NEVER shows the ItsyBitsy.

I have the Arduino IDE for version 1.8.13 (ONE THREE!) on a different computer and when I bring up the Boards Manager I can indeed see ItsyBitsy boards as options and can Install them. But on THIS computer neither IDE 1.8.4 nor 1.8.15 allows for installing ItsyBitsy boards.

What's going on? Is the Itsy Bitsy no longer supported???

That’s a question for Adafruit. Did you follow their instructions?

https://learn.adafruit.com/introducting-itsy-bitsy-32u4/arduino-ide-setup

In particular, while the "library manager" can have people "submit" libraries that will show up automatically, the "board manager" requires that you add URLs for the board manufacturers in the preferences dialog.