sziriusz12 he is saying that your map is in early access and it's pretty much empty and it's already 3.5 gigabytes which is way too big for an early access map. At least that's what he is saying.
Guess he fully understood, what the problem is.
Let me mention that you did something wrong in the optimization (likely that you used hi-poly ballast or tracks, IDK) because the map is 3,5 gigs in this pretty early stage...
He didn't. When building large maps the filesize increases simply by occupiing the terrain. So when he is filling the map with streets and houses, the file size won't increase that much.