screw the male part to the window and insert the female part.
open the window and hold the male part against the wa...ll.
Now close the window [keep male part at the wall, either use small hands or a hex key (size 8 or 5/16)] and mark the hole of the male part to the wall.
Drill a hole into the wall and srew the male part into it.
For orientation of the two parts along the screw axis see picture.
I used PLA and made some more because i thought they would break but they are intact one year after installation and get used quite frequently.
You could also print them in semi flexible materials like PA-CF.
Depending on your windows maybe predrill the screwhole to not damage the frame.