In short: lighting, damage and aging, story and finaly color correction.Lighting: since this is a small scene i would bake the lighting since it will look much better. Also, consider using a hdri instead of the bog standard UE sky.Aging: the wear on the building shows some aging but the modeling doesnt show that. Every edge is very sharp and straight, no sagging, no edge chipping, no cracks...Color correction: i suggest trying some LUTs and see if you can get something interesting fast. Your scene leans towards that dark and depressing style that one can see in games like HL2, the last of us, etc. But its not dark enough and maybe could use a slight greenish-blue tone. Here you can play with values all day long and at some point you will get something interesting.Last thing that i would mention, maybe add more props and set dressing in the station area. Its very basic and definetly needs attention.
Edit: find an image (game, movie, real life) and use it as a mood reference. Usually people use refs to model/texture but they forget to get good refs for mood.Edit edit: forgot about story but thats self explanatory. What is the story of this place?
Good job so far. The material and mood suggest something old, but the lines of your mesh are perfectly straights. Add some chaos. Old things will bend and lean.
Better but the lighting looks weird especially in the second to last screenshot. Are you using dynamic lighting?Also, the ivy on the building doesnt have any shadow so its just floating there. Try increasing shadow resolution or adding contact shadows.
Maybe try a test bake and see how it looks. For that you need your meshes to have lightmap uvs and you need to set those lights to static. After that just hit build lighting and you should get an idea of what it could look like. By default the lighting quality is set to preview so dont expect it to be amazing. You can find more info about building lighting in the Unreal lighting academy series.