If you want to contact support about DMG downloads (since you don’t have an active support plan) I expect you would need to purchase an ASC, or do what BScout suggested and try unpacking on an older version of OS X.
A reminder DUC is not Avid support. If you really need/want to contact support you should open a case there, which you may need to purchase an ASC for.
And the external links for support about licensing is the second link here:
https://www.avid.com/learn-and-suppo...-music-support It can take you on a roundabout journey ending back at the same thing again. But if you are careful you can get to the "submit a question" and provide additional info... that can open a support incident for licensing questions. But I have a bad idea that is not available to you if you don't have a current support plan. I mean it beggars belief they can't throw those enquiries into a queue and have a sales focused person pull out the sales help questions and ignore/cancel the others if needed.
The way to bypass that if needed is to purchase an ASC (Avid Support Code) and file a normal technical support case, (first link on that page) which is pretty offensive to talk to somebody who really should be a sales rep. And within your Avid account the "talk to support" link is broken (at least it is for me) and ends up with a 404, but you also likely don't have a support plan so would need to buy an ASC there. Getting to Avid support is so f***** up it's unbelievable. Whoever runs that organization has to be an incompetent utterly useless clown, how long do you live with web links all over the place broken, circular flow loops, and people trying to work out what they need to purchase going around in circles like this. But I'll have money on betting they have engineered things so their call stats, backlogs, response times, cost per incident, and NPS *look great*. If so then the person they work for is the idiot. HENCE AGAIN WHY I STARTED WITH SUGGESTING YOU CALL A SALES REP AT VINTAGE KING.
Or maybe Jeffro or others can help out. Does your Avid.com account use the same email address as you are using on DUC? (So people can find your account…)