It is a new Frigidaire unit and the only specs I found on it were as follows: "All electric cooktops run off a single phase, 3-wire or 4-wire cable, 240/208volt, 60 hertz, AC only electrical supply with ground."
A 30A circuit would be legal, but a 40A circuit would afford some cushion and allow for a larger unit to be installed in the future.
A 30A circuit would require #10cu or #8al
A 40A circuit would require #8cu or #6al (possibly #8al depending on installation/application and code cycle followed).
Do the instructions mention a "4-wire" feed, or anything about requiring a neutral?
OK, so this is a straight 240v appliance. The 4-wire illustration is only there for installations where this unit is replacing a unit with a 4-wire feed.
For your new circuit you would use 10/2 or 8/2 cable. IMO for what you are installing 10/2 is fine. Especially considering the short distance and that this is brand new unit. Any future upgrade, while unlikely any time soon, will not be very hard.