Can you post a screencap of the SP result and your maps, because the output in Arnold seems very flat i.e. metalness, specular highlights or roughness are imo not apparent? Also I'd advise, taking another look at your export settings as well.
I guess a piece of advice that would be a drop in the bucket here is to not render your assets with offline rendering (vray, iray, arnold, cycles, etc). Doesn't give an accurate representation and visualization of how your asset would look in a realtime renderer/game engine.
I want to achieve renders like this stock photo. But all of my renders always look like they are made of clay for ex. and not steel or iron. Am i making errors in Arnold settings, or do i need to work more on my textures. Or maybe both? Any feedback is much appreciated!