I'm confused by the window kit - help

I have my new portable air conditioner and I'm trying to fit the window kit into my standard living room window.
The part where the hoses go is too short on its own so I obviously expected to have to use the slider.
However - when i put the slider in and make it fit my window - the slider covers up the exhaust hole.
What the heck am I missing - it doesn't say you might have to cut the slider shorter - yet I can't imagine covering the exhaust hole and i'm not even sure I can make the intake adaptors fit with the slider covering the hole.
Help please.
signed
probably an idiot.