Guys, can you tell me how to place teleports? I've been sitting here looking, and I see some groups with numbers, but I don't understand what they're for.

Teleports are grouped together (these are the numbers). One teleport transports the hero to another teleport in the same group.

Added after 19 minutes
Recently, while digging around in the editor, I found the following line in the hero properties (select a hero, main properties/shared):
isscenariohero
and I assigned it the value false for all Dungeon heroes.
The result was as follows: on all maps (including downloaded ones), some of the campaign heroes (Rai'lag, Shadia) can be hired at the beginning. The rest don't want to be starting heroes (I don't know why), but during the game, they can be hired in the tavern. The above applies to heroes of all other races as well.

P.S. I have Heroes v.3.0, but this is probably also applicable to other versions.