Set up an IAC-Bus (virtual Midi Port) on Mac Systems

first you have to start the "Audio Midi Setup" on your Mac.

You'll find this under applications/utilities

under the Tab "Window" click on "Show Midi Studio" and the Midi Settings Window will appear.

click on "IAC-Driver" to create a new virtual IAC Midi Port.

check the "Device is online" box, then go to the (+) to add a new Midi Port and name this for example "to Live"

Now you'll find this Midi Port inside the Midi Settings in Ableton Live.