Rating system for online games in Heroes of Might and Magic IV.

Okay... but it seems there's a nuance, and it lies in this:
It seems to me that VGAplanet is an online game in which more than 2 people participate, and accordingly, places are taken in a match, and these places are taken into account in the ranking.

That's essentially how it is. So what? The main thing is that at the end of this match (tournament), we get a distribution of the participants' places, and then, based on the places and the number of participants in the match (tournament), we calculate the rating.

A Heroes 4 tournament (as well as any other) involves a 1-on-1 game, and there are several such games (round-robin system). Accordingly, only 2 people participate in a match (i.e., 1 game). There will be many matches, but there is only one place.

So what? You run the tournament to the end, where you calculate points for all participants depending on whether they won/lost/did not show up. At the end of the tournament, you calculate the final results for everyone and distribute the places. And how is this different from the final in VGAPlanets? You have the same initial data - this is the distribution of participants' places and the number of participants in your tournament. You take the calculation system and assign a rating to your players for this tournament.

So, this formula needs to be adapted for Heroes in some way.

And why do you need to adapt anything now? You just need to understand where they get the number 6000 from in the formula. And maybe it will also be suitable for Heroes in online tournaments?