The Fill Polygon Tool feature is to populate a blast pattern within a selected polygon quickly.
A reference point is required (this aligns the first hole of the pattern on this point, it can be inside or outside the polygon). Use the 3D Point Tool to add a reference point. Open the fill polygon tool, select the reference point, then select the polygon and required hole type (hole type defaults will determine your burden and spacing). You can use the bearing to rotate the pattern to the desired orientation.