From googling " mobility scooter" model :- Active care Catalina. Instruction manual . this carries a person up to 4 MPH, with 10" diam wheel rims (have to add abit for the tyre thickness)
Motor Two 24V x 320W x 4600rpm
Controller Dynamic A50A
Batteries Two DC12V x 36AH
Soo, 2 X 320 W = 640 W, using your 12V battery = 640/12 = 53 A.
Wheel centre = 10", = 14" diam over tyre. So in one revolution does PI X 14 inches ~ 40 ", So for 4 MPH wheel does 4 X 5280 X 12/40 REVs ~ 6336 revs in an hour, so does ~ 100 RPM, so motor is rated at 4600, wheels need 100 RPM max so gear ratio is 46 :1.
So to under line the points, to carry a person (200lbs ~ 80 Kg) at 4 MPH (stiff walking pace), you need to drag a peak current of 50 A from a 12 V and use a 40 :1 reduction gearbox between the motor and 14" (overall diameter) wheels.
I am not sure that the kit you have is up to this.
Frank