Super bad optics, perfectly fitting, easy installation.
The spoiler is ready for painting possibly you should sand it.
The best way to fix the spoiler is to glue it on the grill. Before gluing, you have to move the grill screws, put only two screws (one for the left, one for the right side) on the bottom line of the spoiler in the lamp beam behind.
You should only glue, if the grill is fix, because you have to look after the same distance between car body and spoiler everywhere.
car body glue or Sikaflex