Whirlpool Bathing Pool

Whirlpool Cadet Elite 5x36
2771e series

Installations instructions say that:

"The Wirlpool should be installedin a 120 vac, 15 amp dedicated circuit. The circuit shoudl be hard-wired from the electrical power supply panel. The circuiy mut be a three (3) wire circuit from the electrical supply. A grounded beutral wire and a third wire, earth ground, are essential."

and a separate 15 amp GFCI outlet is showed in a graphic.

Question:
Can I put Type UF 2/12 grounded from the main box to an 20 amp GFCI outlet?

They require 15 amp GFCI... but the Main Box is 200 with 20amp breaks (but two 30 and one 40)and wiring is Type UF 2/12 grounded in the whole house (but two runs of 10 and one of 8 for the 40).

What could happen If I do it this way?
If they require 15amp... and I put a 20amp break, wire #12 UF grounded and 20 amp GFCI instead... could I lose protection in the tub?
Thanks in advance.

 

Yes, but use a 15-amp breaker.