I have currently bought the DB G6 Diesel Shunter Add-On. but for some reason if go to my layers in groningen zwolle is says that I don't owned it so I can't enable that layers. i don't know what to do becuase i have bought the DLC but for some reason its not working.
Have you Rhein-Ruhr Osten route if not then the g6 will not layer into anything. You have to own the intended route its for before it will layer into anything.
to answer more precisely, loco-addons before TSW3 require their associated home route to function in-game. this is not the case for loco addons released for and beyond TSW3, as content is used from the Training Center core route, and tutorials for those are also on that route.