The owner's manual has jacking instruction. Remove rear wheel Remove the two existing fasteners, as mentioned in the instructions. We had to use a T-25 Torx bit on ours, but maybe a tight fitting hex wrench can be used. Mount the splash guard at these two holes using the original fasteners, which are far more robust than the ones supplied with the splash guards. Don't tighten the fasteners yet.
Test fit the splash guard to the contour of the fascia.
My holes did not line up when I positioned for best fit. You may need to elongate the two upper mounting holes. Elongate as needed. I used a rough rat tail file and a knife to trim afterwards. For each of the lower holes in the splash guard, use one hand on the inside of the fender to draw the fascia into the splash guard as far as it will go.