I live on the fifth floor in an apartment building where the windows have a metal frame. I bought a Frigidaire air conditioner at Best Buy and the screws and installation manual are based on a wood frame.
The screws are just for an L-shaped piece of metal designed to lock the window's position, and also screws that hold the "accordion" side panel thing in place.
I don't want to violate the lease by drilling the window, and I'm not even experienced enough to try that.
Is it really necessary to install the window lock, or is pushing the window down to meet the air conditioner enough to hold it in place? What I have now is a sort of telescoping curtain rod pushing the window down on the inside.
How else could I lock the window in place if I wanted? It seems sturdy, but I don't know...
Here's that section of the manual for clarity: