Welcome to our forum.
That spa is a 220 volt (only) tub, and requires TWO circuits. One feeds the heater only, and the other feeds everything else in the tub. I believe the 30 AMP breaker will feed the heater, and the 20 AMP breaker will feed the rest - and these are two-pole breakers.If you hook it up with a 110 power cord, you will get exactly what you described.HTH