Hi @Qaex, AoE:DE does not currently support transfer of custom scenario files like AoE II HD. It is my understanding this feature is on the dev list. In the meantime you should be able to share the file via email with your friends and play custom scenarios that way.
@Qaex -> We have the same problem with the szenarios at the moment, wana play this in multiplayer game, but it doesnt work with other guys who doesnet have the map config. Its realy important i think, because the standard maps are boring. Hope they will fix this soon.