The guide says minimum Hardware 5 and Firmware 75.08. Firmware and hardware are two different things. You can always update a firmware, but the hardware itself you cannot.
This vehicle should actually work on 4.18 if installed with a separate remote start unit. Ideally I would just update the unit anyway, this allows you to have a lot more options available in your evo-all (such as stand alone, evo-alarm, the different datalink protocols etcc since they didnt exist at 4.18). I have seen you post stuff here before so I assume you have a flash-link? just update the EVO-ALL.