I would provide a link, but I can't. Although, in principle, you can type "maps for Heroes 4" into any search engine, and it will give you a couple of decent websites.
Right now, I'm not only working on scenarios, but also creating a mod that improves the game. The latest version is 3.55. It's a very interesting thing that allows you to look at the fourth installment in a new light.
Regarding version 3.55. IMHO, it's a bit raw... I tried playing "Circle of Life" online with Ksa47, and it keeps crashing (I also tried it with "The Wanderer" - it crashes during battles)... Either the wrong spell is applied in battle, or some other nonsense happens... Until they fix it, it's better to stick with 3.51...