I suggest mixing materials instead of having everything concrete. You could also put a brick texture over that concrete to give it a nicer look, personally what I’d do is add metal pillars near or on the walls to give it a more reinforced look. The Entrance Zone (you misspelled it) is typically located around Sector 1 and 2, which, are the more industrialised areas of an SCP site. For this, I would recommend you make it a slightly bit brighter, and adding more props as it gets boring looking at the same pipe racks and barricades over and over.
I would also recommend adding a variety of colours, instead of just smoky grey and medium stone grey over and over.
This ceiling could use a nice skirting and glass too, it feels really off without it in my opinion.
You certainly have a good start, it just needs to be improved.