The Andersons 21-3-8 Fertilizer with Barricade Herbicide is not labeled to control dollarweed. It offers residual control of a wide variety of susceptible weeds and it works by preventing germination of weed seeds and stop them from developing.
If your spreader is not on the label then you will need to calibrate your spreader. We have a video here to help you calibrate your spreader before treating the entire area.
The Anderson's 21-3-8 Fertilizer with Barricade Herbicide is a slow-release fertilizer and pre-emergent.