How do I record - eg guitar - into scaler using iPad microphone?

Using scaler 2 on iPad Pro. I want to record acoustic guitar directly into scaler through the iPad microphone as demonstrated on one of the tutorials on YouTube. When I press the record button on scaler the “waiting for input” message just sits there - so scaler is not picking up anything from the iPad microphone - what am I doing wrong?

Maybe the input level from your guitar is too much low
have you tried to move the Scaler slider on the left?
There is any movement in the audio level (the line below the red arrow)?
The little blue dot is the current threshold: you can lower or raise it

Welcome to the forum @Bluep0wder Apart from Claudio’s suggestion have a look in your iPad settings and make sure Scaler is allowed to access the microphone.
You can check this under Settings > Privacy > Microphone.