Demo: Architecture Design Challenge is a practice panel, not a competition you have been asked to judge. It is put in front of every member who opens the Evaluations page so that the scoring interface can be tried out before real entries are at stake. Nobody nominated you for it, and nothing you do inside it reaches a real competition.
Why it appeared without anyone adding you

Your Evaluations page asks for your live assignments and the practice panel in the same request, and your account is added to the practice panel the first time you open the page. That is the whole of the story behind the card. It is not an assignment that arrived without an email, and it is not left over from a competition you once judged.
The card carries a Practice Evaluation banner, and the panel repeats it above the entries and above each entry you open.
What is real in there and what is not
The interface is the real one. The entries are samples, the criteria are ordinary criteria with their own minimum and maximum, and the sliders, remarks and Save Score button behave exactly as they do in a live panel. That is the point of it: the practice run should teach you the tool.
Everything that leaves the panel is discarded:
- Scores you leave are marked as practice. They do not enter any competition's results, they do not reach any author, and they do not appear on any leaderboard.
- They are deleted after 30 days. You do not have to clear them up, and there is nothing to withdraw.
- Judging it does not credit you as a juror. It puts no jury badge on your profile and no jury credit on any competition page.
The practice panel has no closing date, so it stays on your Evaluations page for good. It does not expire and it is not a sign that something has gone wrong.
Seeing only the demo means you have no assignment yet
This is the part worth being clear about. The practice card is not evidence that a real assignment exists. If Demo: Architecture Design Challenge is the only card on your Evaluations page, you are not yet attached to any competition's evaluation round, and no entries will appear until somebody attaches you.
That is a specific request to make of a specific person, and your juror dashboard is empty sets out the wording and who to send it to. If you cannot find the Evaluations page at all, start from getting to your juror dashboard.