The AudioBox i-Series must be connected the correct way or it won't be recognized.
Please review these instructions on how to make the connection work:
https://support.presonus.com/hc/en-us/articles/210044883-How-do-I-connect-my-iPad-to-the-iOne-or-iTwo-
You also need to grant Microphone access for the iOS device to pass audio from the interface to the audio recording application.
On your iOS device go to Settings --> Privacy --> Microphone --> Capture (make sure slide is Green)