Sorry, I am afraid I just can't make heads or tails out of how to set up a challenge match.
I have tried multiple times to set it up and each time I am presented with the same message that the user "stefanozanotti1" does not exist.

If someone else can give me some clear instructions on how to do this, then I will create the match. Or it stefanozanotti1
cares to create the match that will be fine also. Otherwise, to Hell with it and he can go on to the next level.