It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

The Battles of Destiny map editor actually shipped with the game, but was not accessible via the DOS Box. GOG has fixed this, and you can now make your own maps! Instruction for using the Map Editor start on p. 61 of the manual, and I plan to livestream some examples of how to use it.

There is an image attached showing the new startup screen. If you do not get this option, uninstall Battles of Destiny (you will be able to keep your saved games) and reinstall it.
Post edited June 09, 2022 by HDIAndrew