Altium Clearance Constraints on USB Receptacle Footprint
From the notes on the footprint definition the cross hatched areas are the solder pads, not the solder mask area. The white rectangles over the five signal pads are the actual connector pin fingers and you would find their dimensions on the connector drawing. 

According to what I see the signal pads are all 0.4mm wide and 1.2mm length. Center to center spacing between these pads is 2.6mm/4 = 0.65mm. This leaves a total of 0.25mm between each pad. This is equivalent to a 10mil clearance if you think in typical USA type units. You need to set your pad to pad clearance rule to 10mils (0.25mm) or less.