you seem to mix a lot of stuff up. It is fine since you are not fully aware of the workflow yet.
But, please let us explain it to you a bit further ;-)…
The Dolby Atmos Renderer is a standalone software which is only on OSX (as you know and understand). This leads to the fact that this is not yet possible to run on any PC at the moment!
The Dolby Atmos Renderer VST Plugin inside of Nuendo is a VST solution which does all the needed “rendering” to produce a proper MASTER (ADM BWAV) within the Mixer of Nuendo. It is a VST Plugin that gets its audio stream within the Mixer of Nuendo - so ASIO is for sure a part of whole the audio system but not as in any driver or external input/ output at this stage.
Currently this VST Renderer is NOT able to create a MP4 (as the standalone version is) as well as create a Dolby based binaural mix. We all hope this will come in future updates of the VST Renderer.
If you need to have any MP4 or a Dolby binaural mix you need to export your mix as BWAV from Nuendo and import this into the standalone version > there you can export all you need.
Of course you need a OSX system as well as the Dolby Atmos Production Suite.
So, to create either a DOLBY binaural mix or an MP4 you will need the real standalone DOLBY ATMOS RENDERER at this point! All this comes down to Dolby which just didn’t include these functions into the VST version… yet… lets hope for the best!
Btw, Atmos mixing has nothing to do with MP4, or binaural mixing… a proper binaural mix could be created by other plugins like DearVR Monitor and so on… the MP4 export from inside of Nuendo would be a nice feature, but still this is not what atmos is about …
all set? Cool !
To answere to this: you don’t need any extreme hardware when you stay within Nuendo and use the VST Renderer.
BUT - if you still like to use the standalone Dolby Atmos Renderer and NOT the VST version you would need something like a DANTE card (128 i/o) or a MADI card on your system as well as on the OSX system hosting the standalone renderer. Look at it more like a hardware box with 128 i/o you need to send audio too … sounds expensive? It is! Thats why the good people of Steinberg (together with Dolby) came up with this VST Plugin that lets you do it all withtin Nuendo - cool eh!
all the best
Another very basic video to see and understand how to do it inside Nuendo:
You might check his stuff, very basic and very easy to follow and understand the idears …