Is this a stupid question? Am I missing details? Is this thing on? Ha
For future reference for anyone with a similar problem, I did get it to work albeit in a roundabout way. I opened QuickTime and set it to record a new video. There are options to select both audio and video and I set both of those to my iPad. Using QT in conjunction with OBS allowed the audio to come through. Note that you don't have to actually record via QT. You just need to have it open.
I don't think this is ideal but in the end it works. I'm still hoping someone has a solution entirely within OBS. Thanks!