Update error

Please after I downloaded iPhone 6 Plus ios 12.5.4 to update on my iTunes on my pc. It can’t extract the firmware to restore the iPhone but it only remains there and it’s can’t progress toward to update the iPhone 6 Plus….what is the cause of it….and am using original usb light cable too. I downloaded the iOS from the site called Ipsw.me. Please help me I don’t know if it’s from the iOS or the iPhone 6 Plus.. thank you