Hello Chris,
I found these pages that explain how to set up multi-channel audio output from a plug-in (e.g. Hauptwerk) in Logic:
https://documentation.apple.com/en/logicpro/usermanual/index.html#chapter=27%26section=12%26tasks=true
http://www.soundonsound.com/sos/sep07/articles/logictech_0907.htm
The Hauptwerk plug-in has 16 stereo output channels (i.e. 32 mono channels in total), which can be selected as audio output device channels for the Hauptwerk AU/VST Link 'device' on Hauptwerk's 'General settings | Audio outputs' screen.
Note that if you *only* wanted to use Logic for recording/playing/live *audio* from Hauptwerk (but not MIDI) then the 'Using an AU/VST host to apply real-time reverb' section in the main Hauptwerk user guide (pages 183-184 in the current v4.2.1 version) would be the instructions to follow, rather than the Logic tutorial on the website. (The Logic tutorial on the website covers recording/playing/live audio *and* MIDI, which necessitates a much more complex configuration.)