Remove the large plastic cover at the top of the frunk, near the windscreen/windshield. It just snaps on and off, no tools are needed.
This reveals the intake for the AC; first try a 'dry fit' by placing the intake filter in place. If the area where the adhesive tape will make contact is dusty or dirty, first clean it with a damp cloth and allow to dry.
Now remove the red film protecting the adhesive foam and simply place the cover in the intake opening