I'm getting a similar error.
AUSST can no longer download CCM patches (the Acrobat ones seem to still be working)
Looking in the Error logs, it's gettong Server 500 error's from the ccmdls.adobe.com site

If i try one of the downloads manually I get 

Access Denied

You don't have permission to access "http://ccmdls.adobe.com/AdobeProducts/AUDTBETA/22.1.1.1/win64/1aa8e746-f6fe-40a3-bcb0-2cdd130f6a05/AdobeAuditionBeta13All.zip" on this server.

Reference #18.4658d617.1635983747.b834242

I have tested this on a non-work pc (so no proxy at all) and get the same error