There’s a suggestion from billw58 here: Problems Getting Sound into Audacity - #4 by billw58
By default, Apple blocks all apps from using any audio recording devices (they use the term “microphone” to mean any audio recording device), unless it is Apple software (as is the case of Garage Band) or purchased through the Apple Store. It’s becoming increasingly difficult to provide free open source software for Mac users - our developers have to pay a fee to Apple just so that Audacity will run on modern Macs at all 