If you have a 32-bit Mac, then you won't be able to download a 32-bit version of Audition. Adobe, under direction from their legal team, have been told only to make the current version, and its -1 available. And all the recent versions are 64-bit only. Adobe's policy is non-negotiable, and we aren't allowed to discuss the reasons why.
You haven't said which particular Mac you have, and around that time this became a significant issue for a lot of users.