Yes, that is correct. Each person staying on property will receive a room key. Yes, you do have to pay extra for more than 5 people to a room, I do believe it is $25.00 - but check!!
Each key will have the dates of your stay, your name, and age, and are used for fotl for the entire stay, including the entire day of check out -- ( check in as early as possible, even if your room is not ready, and enjoy the parks on that day as well, the hotel will hold your luggage for you.)
Another tip, we purchased lanyards and brought them with us, at check-in the person punched holes in our room keys, we then strung them on the lanyards and wore them around our necks -- (see photo) this way they don't get lost, and no one has to keep up with all of them!! ( Yes, even our little one who was 3 got one too!!)