Halo: NightFall

So when i got my xbox one my family games so my dad uploaded The Master Chief collection to the xbox and Halo: Nigh Fall also so it is on the Halo Channel on my xbox but when i go to watch it, it say i have to buy it but when i click to buy it, it says that it is installed so does it mean that i could only watch it on my dads account cause i want to get the bonus armor but if i can’t watch it on mine i can’t get it so what should i do