Mine is on Steam... I started Steam and went to my library.. when I clicked on Syberia3 it showed it was downloading an update.... after it finished downloading(mine took over an hour but I have a very slow internet) I clicked the Icon on my desktop the game started and my options were to continue(as I am still playing the game) or the last option is Downloadable content..... I will click on that now as I just finished the game.
Hope this helps...