Make sure to adjust the pitch to fit your vocal range.

I did that already

Are you having trouble with any other microphone games?

Hmm, for me it has always shown me red notes of what I actually sang if I got something wrong. Are you not seeing that?

Did you give ToneGym permission to access your microphone? I get a pop-up about it every time I sign in on a new device.

for me, I was singing an octave up about the first 3 times I tried the game. I was totally confused, and, like you, it only gave me those red notes and I had no idea what I was doing wrong. one day it clicked and it has worked pretty well for me since then. maybe you're having the same issue (singing an octave up or down from the reference). best of luck!

It does provide feedback in that the notes which were incorrectly sung light up in red and it tells you what you supposedly sang, using solfège as the key. However, I've found that it is sometimes wrong and is therefore not a helpful feedback feature - quite the opposite, it can be damaging if taken too seriously.