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

First, make sure that your Logic project's sample rate matches that of the sample rate you set in the Dolby Atmos Renderer, either 48 or 96kHz.

Next, in the Logic Pro X Preferences in the Audio Tab, select Dolby Audio Bridge as your output device. Now set the I/O Buffer Size to 1024 samples.

In your Logic project, insert the Dolby Atmos Music Panner on a track with audio or an instrument loaded. Assign that track to Output 11.  Now, in the Music Panner UI, make sure you are connected to a renderer - the connection status indicator should be green. Next, use the Object selection drop down menu to select or enter Object 11. Now start playback and you will be able to move and position this Object.

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 Object 12, the output of your track should be set to output 12

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