That URL contains source packages that need to be self-compiled into an OS image: compile [LibreELEC] - Neither LE or previously OE has ever supported ISO install - only USB. Our USB/SD creator app can make the USB from the self-compiled image.
In case it's not obvious, we have no desire to support i386 hardware so without intending to sound rude; this is either something you figure out for yourself or quit the idea of recycling ancient hardware and invest in a cheap Raspberry Pi kit that will be 20x better to use.