All questions regarding mapmaking for Heroes of Might and Magic 3: The Shadow of Death.

Looks like it's not working again. Problems:

"All artifacts on this map are either reserved or prohibited."
Artifacts are reserved when they are a special victory condition or a quest objective. Artifacts can also be prohibited in the 'Map Specifications' dialog on the 'Artifacts' page. There must be at least one artifact that is not prohibited and not reserved.

And how do I specify it? Please advise.
Map Editor version 2.00 "Armageddon's Blade". Discovered when trying to create a "Bring Artifact" quest for the Soothsayer (artifacts are also not displayed in the quest form).
and also:
I enter the description in the properties. The only error in the map (mentioned above) is present in all original maps, and it is the same when checked.

And thirdly, how do you disable the standard victory condition ("defeat all") in the SoD editor if you only need victory based on the "obtain artifact" condition? The necessary checkbox is not displayed in the window! And the game says "obtain artifact or defeat enemies".

Simply, the game doesn't see the point in aimlessly running around the map if you have already defeated everyone... As an option, you can create a map with only one player, who will have the goal of finding something and the defeat condition - time runs out... By the way, are you setting this limitation?
Yes, it's annoying that the forum kicks you out when you are inactive (collecting screenshots). I understand that this is relevant for banking sites, but here!?
Added after 12 minutes
Yes, and what does "main hero" mean? The one you specify in the defeat conditions?