How WiFi Hotspot works in PC? Why can't I access blocked app in my internet even sharing connection through laptop?

I'm having trouble for long days. I reside in a hostel provided by my college and I'm using the internet connection of my own college which has it's own server, as said by others. I'm given a username and password for the internet. The internet uses captive portal login and to get an internet connection I've to use my username and password. Every time I disconnect from the internet, I've to again login to the captive portal and this continues. But if I connect to my laptop and turn on the hotspot, I don't have to login to the captive portal if I'm using it through mobile. How actually the hotspot works?. If hotspot is all about sharing my pc's internet connection ,then why i can't i access blocked apps?. Also, they've banned all the users to access games like PUBG. How can I get access through it? VPN didn't work. I also used a paid VPN but it fails. If hotspot is sharing my laptop internet connection,why can't i access to blocked sites?. Thank you in advance for your answer 🙂