Where does it say the volume? And even at that volume you could keep 4 koi in there, tops, and that would be pushing it. Understocking is the key to success in a koi pond.
Heating up for human body temp and heating up for koi are two different things. Our body temp is something like 97F. Anything under 80F is going to feel cool to us because of the large temperature difference. Whereas 80F is rather hot for a koi. My pond is 4000 gallons, completely shaded, and in the ground, and it still gets around 78F in the summer.
Another problem I have with this, what about a puncture in the sides or the risk of collapse? We've all seen videos of these things collapsing on kids in the backyard. Many of the koi QT tanks that look like this are resistant to UV light which degrades the plastic. What kind of protection does the plastic on this have? I know sometimes we can get away with using things that weren't intended for fish, but I don't think this is the case.
With the new filter you will have to buy (in a pond this size without any waterfall, you're going to need a pretty strong filer) plus the industrial heater, you're looking at a very expensive experiment that could potentially go really wrong. I hate to be a dream-dasher, but koi and ponds are a whole different level of aquarium keeping. If you really want a pond, I suggest you get in contact with a local pond-builder (they will know things about your area that you wouldn't think of).