Light and map problem

Hi everyone. I’m pretty new here and I got tow issues while I introduce my model in Unreal. They are really basic.

I got a closed space, with no windows but still the light is getting in. Do you know why this happens? I model my 3d in rhino and then passed it through 3dsmax to unwrap the volumes (in fact I don’t know if this matters).

I also would like to know why the UVW map grid has so different sizes in the different objects. The objects are organized by materials and I have been playing around with some values in ·dsmax but nothing changes…

Thank you in advance!!