It looks like your windows are completely opaque. You need to assign glass material to them. I'd recommend to find appropriate material in Corona material library, or use glass preset in Corona physical material.
As for the optix warning issue, it could be because you don't have supported Nvidia card, or maybe your graphic drivers are very outdated, or corrupted. That means that you can't use Nvidia fast AI denoiser, but otherwise it should not impact your Corona usage in any way.