Current questions and answers regarding the map editor.

In the Kind property, set it to COLLECT_RESOURCES. In Parameters, first specify the resource type, and then the quantity.
Also, a script will be needed, to later remove these resources, but it will be simpler, specifically:

function Sera_Gold()
  if GetObjectiveState(objective name)==OBJECTIVE_COMPLETED then
      SetPlayerResource(1,SULFUR,GetPlayerResource(1,SULFUR)-20);
      Trigger(OBJECTIVE_STATE_CHANGE_TRIGGER,hut objective name, nil);
  end;
end;
Trigger(OBJECTIVE_STATE_CHANGE_TRIGGER,hut objective name, "Sera_Gold");