It was chosen as a drop in replacement for a LM7805AC regulator for more current!
I assume you're testing without a load at the moment, but if you get it working make sure you have an adequate heatsink. These things are often more-limited by power dissipation (converted to heat) than by current alone.
...In case you don't already know this, power is calculated as Watts = Voltage x Current, and in this case it's the voltage dropped across the regulator. For example, if you feed 6V into the regulator there is 1V across it for 2W at 2A. But if you feed 12V into it that's 7V across it for 14W at 2A.
...Switching regulators are more complicated (and they need an inductor to store energy) but they are more efficient because the main-controlling transistor or MOSFET inside the chip is switching completely-on and completely-off so it never "sees" voltage & current at the same time. (Of course the switching is filtered/smoothed so you get constant DC out of the regulator.)