A surface texture is a texture that contains AO, Metallic, and Roughness all in one, the AO is in the Red channel, the Metallic is in the Green channel, and the Roughness is in the Blue channel.
Btw, it will never be exactly the same as it is in 3DCoat, the same as it will never look exactly the same between 3DCoat and Blender, or 3DCoat and Substace Painter. Because they all use different renderers and shaders, the best you can hope for in any engine is an approximate similarity.
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