While those casters are better than the tiny 2-3" solid ones, they still won't roll over crushed gravel very well. You may be able to use a tow strap and pull the dolly across the gravel with an ATV, lawn tractor, pickup, whatever you have... but I don't suspect you'll be able to push by hand a 600+ pound load over anything but a paved surface with those. How long is your driveway? If plywood wasn't so expensive, you could lay a couple sheets down for a temporary surface to roll things across.

Otherwise, I suggest asking the freight delivery drivers to back into your driveway if possible. Many drivers are more than accommodating, if they have the space to pull it off, despite what the fine print in the terms of the sales-order states. Good luck!