There are 3 of us staying here, but the room is only prepared for 2 people.
There are 3 of us, but there are only amenities for 2.
There are 3 of us = 私たちの3人いる
Staying here = ここに泊まっている
But = だけど、この場合は”なのに”というニュアンス
The room is only prepared for 2 people = 部屋は二人分の用意しかしていない
There are only amenities for 2 = 二人分のアメニティしかない。ここは明らかにわかりますので、”people”を省略しても大丈夫です