Sketchup model won't show applied materials correctly!

I wanted to create a level for my game in Sketchup since its the only 3D modeling software that I know how to use...at all. But I decided to create a simple house-like test model to see if it works first. I imported the model into Unity, generated colliders and UV maps and unticked "import materials" since i didnt have any textures on my model. It imported fairly ok... other then the fact that some faces were invisible (but its no problem because I know how to fix it).

The problem is though that whenever I try applying a material to the model (a material that was made in unity) it does not render it at all! It only gives the object a different color. I made a video to show you guys.

Link to video: https://youtu.be/sbgdubYtpbc

Note: Exact same thing happens when I tick "Import materials" if thats any help. I have no idea how to properly create game ready models.