Sure, the HPWC is configurable (at install time) for a maximum current. You'll have to set it to the 80A setting which will give you 64A of charge current. I would not recommend leaving it on the 100A setting because your 80A breaker will not be rated for 80A continuous load (you'll probably end up with occasional nuisance tripping, etc.)
It looks like your wire might be sized for the full load, so I'm wondering if he's taking into account something else - a load calculation or something... it would be worth asking him why he put an 80A breaker in there. He may have misunderstood the HPWC ratings and put an 80A in there because he calculated 20 kW or something.
