If you can see the Dolby Audio Bridge in Audio MIDI setup but not in the Dolby Atmos Renderer Preferences,  this may be due to an issue with how the UI interacts with the mouse scroll wheel.   If you have a large number of Core Audio devices listed in Audio MIDI setup they may not all display in the Renderer Audio Input Device and Audio Output Device drop down menus.   Using the up/down arrow keys will reveal the full list.