You can use the VST3 version of the Music Panner to create an Atmos mix when connected to a Dolby Atmos renderer. 

First, in Ableton, open the Preferences Pane, in  the “Audio” tab, select the Dolby Audio Bridge as the audio output device.

Next make sure the “In/Out Sample Rate” setting matches the sample rate you set in the renderer. For use of all 128 input channels, we recommend 48kHz .

Set the buffer size to 1024 Samples (2048 for working with 96kHz)

Then select the "Output Config" button, In the stereo outputs column, make sure that outputs 1-130 are activated.

Now, in the session view in Ableton, load the Music Panner onto an audio track. In the Music Panner UI, using the Object Pair drop downs, assign objects 11 and 12.

Now, in Ableton on the audio track, assign “Audio To” to “Ext. Out”, and then specify outputs 11 & 12.

If you want to create multiple objects on different tracks, repeat the steps above taking care to to match your Object and output assignments for each instance of the music Panner, e.g., if you assign Objects 13 and 14, the external output of your track should be set to outputs 13 and 14.

You will now be able to position your objects with the Music Panner.

For detailed instructions on configuring your system, refer to the documentation packaged with the Dolby Atmos Production Suite (or Mastering Suite) and the Dolby Atmos Music Panner.