Make sure you are in a multitrack sequence. If you are in a stereo sequence, copy all the clips in your sequence to a new empty multitrack sequence. A Stereo sequence cannot be converted into a multitrack sequence.
In the Audio Track Mixer, change the number of output channels to 12.
Change the panning of all tracks so they alternate left and right.
Change the routing so that Tracks 1 and 2 are going to the channels 1-2, Tracks 3-4 go to channels 3-4, etc.
When this is fully set up, select Export Media.
Change the export setting to Waveform Audio
In the audio pane, select 48k 24 bit, then change the audio output routing to match your sequence outputs.
In the checkbox near the bottom, select to have each channel output to a separate file.
Hope that helps.
If you don’t understand something, go to the section in Premiere help on how to use the Track Mixer (this is where most people get tripped up).