Ground is not a floor - i think this is related to age if the languages.
In Norway we refer to story and avoid confusion altogether. If its on the 2nd story you press two on the elevator, or walk because you’re not made of cheeseburgers or fish’n’crisps.
There's not usually a 0 (at least in Canada). Ground floor is 1 or G. The floor above that is 2. Basement is B, or if there's multiple basements, B1 then B2, B3, etc.