With at least my version of C:S on MacOS from Steam, this mod cannot be used to create new music packs or stations. That is because the mod tries to execute \~/Library/Application Support/Steam/steamapps/common/Cities_Skylines/Cities.app/Contents/Frameworks/Mono/bin/mono, but that executable does not exist. In my installation, I only have the Mono runtime (\~/Library/Application Support/Steam/steamapps/common/Cities_Skylines/Cities.app/Contents/Frameworks/MonoEmbedRuntime).
I was able to work around this by installing the game on a Windows computer. I then ran the mod to create for me the DLL, which I then copied to my MacOS installation.
With at least my version of C:S on MacOS from Steam, this mod cannot be used to create new music packs or stations. That is because the mod tries to execute \~/Library/Application Support/Steam/steamapps/common/Cities_Skylines/Cities.app/Contents/Frameworks/Mono/bin/mono, but that executable does not exist. In my installation, I only have the Mono runtime (\~/Library/Application Support/Steam/steamapps/common/Cities_Skylines/Cities.app/Contents/Frameworks/MonoEmbedRuntime).
I was able to work around this by installing the game on a Windows computer. I then ran the mod to create for me the DLL, which I then copied to my MacOS installation.
Consider putting the above notes in the README.