Yes, you have it oriented correctly (red light on the bottom right)
This is the only document I was able to find that maps out the range of the sensor. It is designed to be placed about 8 ft off the ground. I use mine for presence detection in various rooms in the house, and is placed over doorways or up near the ceiling. The one in my living room picks up motion from approx 20 feet away without any issue.
If the range is not what you are expecting, you might have the sensor pointed too far down. I find that even when the sensor appears to be pointing straight ahead, it is able to detect objects almost underneath it. If you are angling it down too far it may be looking mostly at the wall.
