Hello,
You are texturing using the Spec/Gloss workflow but UE4 is Metal/Roughness based.
You have to tell us what software you use for texturing so we can guide you better. But for a quick workaround, plug your Specular to BaseColor, Invert your glossiness and then plug it to roughness, Plug a pure white to Metallic slot. You should also add a Reflections Capture sphere to the scene. 