If you haven’t already, try taking a look at the guide (start at chapter 1.4 – recording). http://zynewave.com/podium-guide/
Have you selected an audio input on the track you’re arming for recording? Also, how are you monitoring your input (microphone)? If it’s through Podium, you should be able to see the level meters on your track moving. This would mean everything is set up correctly.
MIDI interfaces are unrelated to this, so you don’t need to be concerned with them if you’re recording audio.