The M-Audio Radium 49 is not officially supported on modern macOS , but remains usable as a basic MIDI controller. For professional or critical use requiring all 49 keys + full controller features, consider replacing it with a modern, class-compliant controller (e.g., M-Audio Oxygen Pro, Arturia KeyLab, Novation Launchkey).
Basically, you get a basic keyboard controller, but the "control surface" features are dead without the legacy driver. m-audio radium 49 driver mac
by selecting "Keyboard Series" > "Radium" on the official download page. Troubleshooting Tips The M-Audio Radium 49 is not officially supported