Texture not working on object

Hello,
I have a project that I’m having a bit of trouble with. Let me try and explain. In short, I’m trying to apply a texture to an object, but instead it is a solid color.

I built a building in “Autodesk 123d design”, and exported it as stl. Then I used an online converter to convert it to obj, then added that to the unity scene. I created a material with a texture and tried to apply it to the object, but it was a solid color.

I think the UVs on the object might be messed up. I tried some things in blender, but had no luck. Any ideas on how I can fix this?

Thanks so much!

Usually the 3D tool you made the object with also uses materials for viewing textures. do that first and when it works export to unity.