How to get the Atreus to work with USB Host Library for Arduino?

I’ve built an arduino HID relay by following this video:

When I plug in a vanilla usb keyboard (i.e., not the Atreus) and run this keyboard example, I do see the key presses in the arduino’s serial monitor:

However, when I plug in the Atreus, none of the keys register.

I suspect the problem is that the Atreus is incompatible with the spi4teensy3 library being used by the arduino sketch, but even if that is the case, I.m not sure what I would need to change to get it to work.

Are there any documents or guides which would be helpful for debugging?

Just guessing, but maybe it’s because Kaleidoscope is emulating multiple USB HID devices, including Mouse & Absolute Mouse.