I think Hotstar app not available in OTT bundle pack for Rs.999 and above fiber plans as per Airtel website. It shows Amazon Prime & Zee5 along with other apps.Rs.153 is for basic NCF pack for DTH service. Even though we are paying Rs.999 for fiber service. You need to have active DTH connection to run OTT apps. If you don't pay min Rs.153pm then OTT apps will be blocked even free apps like YouTube too.
Xstream STB will be provided for Rs.799 or above Fiber plans. You need STB compulsory because the Phone no registered on Airtel is linked to OTT apps subscription. If you don't take STB then you won't get Hotsar,Zee5, Prime Video subscription