The requirement is a browser export, but GDevelop allows you to export to other platforms if you want, for your own use. However, for this competition, it must be exported as a browser game.
The idea is the same, though, really. Just focus on making the game. GDevelop will take care of exporting the right things for it to play on a browser window. Let me know if you need pointers on how to do that, as we have tutorials on how to export and upload such games to itch.