No Audio on Mac when converting 8mm from camcorder

I am trying to convert my old analog 8mm tapes to digital mp4 files. I have no audio on my mp4 files.
I have watched several videos and can't figure out why I do not have any audio. Some of the videos I have watched have said on a Mac you have to download and app called "IShowU" to capture desktop audio. I am not sure if that applies to my situation because I (think) I am not trying to capture desktop audio but rather trying to capture the audio from my camcorder........ please help!
I am using my old Sony camcorder to play the tapes. RCA jacks from the camcorder to a "CAPTURE S-Video & CVBS to USB 2.0" adapter into my MacBook Air running macOS Monterey V12.1. My OBS Studio is version 27.1.3 64bit. My camcorder only has 2 RCA ports on it (one for video and one for mono audio).
 
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