Do the math. The heaviest navigation buoys weigh 10 tons, this looks to be a bit smaller but we'll give the benefit of the doubt.
(20,000 lbs × 3ft up) + (20,000 lbs × 3 feet down) = 120,000 ft*lbs of work done and this is REALLY generous as the buoy will be buoyant on the way down and the generator won't be generating electricity at the top and bottom when the buoy moving slowly. Also, the average strong swell is around 6 feet but the buoy has inertia and doesn't follow the full height of the swell (even without load) which is why I chose 3.
120,000 ft×lbs at let's say 6 times per minute for an average swell period is 720,000 ft×lbs/min or 21 horsepower.
In electrical terms that's 15kW. That's a really bad number and I made all of my assumptions in favor of a higher output and did not consider efficiency at all.
This is a scam just like the gravity battery.
There is a reason these systems use lots of mechanical parts such as ball screws and gears over strictly electrical means of generation, it's to create the appearance of work for the investors.