PROBLEM:I have no idea as to how to make a micro:bit unit programmed with Arduino IDE understand radio data transmitted by another micro:bit unit.
It looks like Adafruit did some or all of the Bluetooth radio stuff, so their forum would be the place to post.
I have found, however, another library that seems to be doing what I want. But I lack experience to understand if it is capable of making the MB transmit and receive any actual user data.
Most all Arduino libraries include examples. The library you posted a link to appears to have a ping pong example, I would guess thats an example that demonstrates TX and RX.
the contents of what's actually being sent there remained mystery to me.
Study the radio library .h file for the details.