You subscribe and it will download automatically. You sometimes have to restart TrainSim to get routes to show up properly and workshop routes only come with quick drives. I think there are other scenarios available for you to subscribe to.
ASUS CM6850, Core i7-2600 @3.40 GHz, 8 GB RAM, NVIDIA GeForce GTX 750 Ti /2GB, Win7 64bit up to date. Acer 23" monitor @ 1920x1080