There is a import option, to import with materials and textures (at the bottom), if that doesn’t import the mats and textures, then the fbx is not optimized. Then just drag and drop the textures into your project content sub folder (Textures), and pick the first texture - right click it and create a material (or use the automatically generated one). Anyway, usually while importing textures, materials are blank (white). In such a case drag and drop the textures into the material editor, then plug them into the corresponding nodes. You also want to add a constant, set it to 0.5 and plug that into the roughness material node.