If I have Traktor Pro 2/ audio 6 interface and now I have window 11 ,and I want to upgrade to traktor pro 4 and I downloaded the software for traktor pro 4 what else do I need to do ?
"Downloading" the software - does not mean you can run it.
Have you actually purchased the upgrade (via the NI Shop) and see it available in your NI Account (and/or Native Access)?
Once the purchases is complete - you should just able to install and enjoy.
VP