Basic schematic scenario

Hi everyone,

I have been working in a basic schematic scenario to show the lighting strategy in an interior design project the way we show in our presentation. It is basically a white background with lighting fixtures in purple and light effect in Blue as the attached below.

however in UE4 it looks like grey even though the material applied is completely white.

Does anyone has an idea or recomendation on how to do this? I dont need lights or anything. In order to make the light beams I created a sort of hologram material and applied oppacity. it is still in progress but I would love some recommendation.

many thanks