If you are on macOS 14.3 or higher, you'll be required to grant Limitless permission to access your System Audio.

Click the Allow button when you see the popup "Limitless Would Like Access To Record Your System Audio". If you do not see the popup, go to your System Settings > Privacy & Security > scroll down to see "System Audio Recording Only" and toggle on Limitless

Restart Limitless and you should be good to go!