Shadow turns out lighter instead of darker

I have been working with Twinmotion for some weeks, yet there is something a can’t figure out how to solve. I have a kitchen with space underneath that lights up, instead of being darker. I tried to adjust or change the materials/reflectivity, but that didn’t help. Also, I made the walls and floor thicker (double layer) to prevent light bleeding in, but this didn’t help either. I have been tweaking adjustments but nothing works. Since I am on a Mac, I can’t use Path Tracer. There is no shadow with Lumen or with Standard global illumination. Also tweaking the shadows doesn’t help.

Anyone familiar with this issue? Any help is welcome.