BMW 5 series EGS EWS is off, so you cannot get isn as it is not there.
You can check on top of EGS isn page the status of mounted EGS ( ews is active or not)
To make the key, You can get ISN from DME ( if it is MSX8X, you need to arrange ignition on to read it, this can be achieved by mounting any cas with a key on this car, or connect dme on bench).