- Generating random maps in Heroes of Might and Magic III: The Shadow of Death.

Look. I downloaded the complete collection and... it says I can't create a map with these parameters. What should I do?

It seems that the map parameters you've set are not compatible with the template.
Each template has its own parameters - map size, number of players. Check the parameters of the template and choose a template with the desired parameters, instead of the one that is selected by default.
There is also a good topic about templates on the forum.