Quick, practical guide — M-Audio Radium 49 on Mac
Some users have had success using old drivers on slightly newer (but still legacy) Intel Macs by following these steps: m-audio radium 49 driver mac
Configuring Your Radium 49 with Music Production Software Quick, practical guide — M-Audio Radium 49 on
If you have an older Mac running Mojave or earlier, you can find the Legacy M-Audio Drivers Most DAWs have a "MIDI Learn" function
Modern macOS (Catalina to Sonoma/Sequoia): There are no official drivers for current macOS versions. Users on macOS Ventura or Sonoma will find the device is not recognized when plugged in directly via USB.