skyrim steam install read description?

Okay today I dropped $60 on the elder scrolls saga collection that has every game from arena to skyrim. I started to install skyrim first because that's the one I'm wanting to install first and when I go to install it after steam gets done doing all its bs it says installing from disk but it says 45 minutes and it keeps climbing. Now I have a mobile hotspot as my internet and it only has a 5 GB limit and even tho it says installing from disk it seems to be downloading the game as well from the internet and not actually using the disk. My question is what exactly is it downloading when the entire game is on the disk? Steam already used nearly 200 mb of my data to update itself and when I turn off my device it goes into offline mode and skyrim stops installing. The disk has 8gb of data on it so I doubt that its just a launcher disk so is it the dlcs or is it a setting I have to correct as to why its downloading? Has anyone had this happen or does anyone know what I should do or try to get this game to install from the disk and not their stupid servers. I should of bought this for a console instead but I wanted to mod like I once did when I had a good computer because now I do again. I'm ranting but any advice would be greatly appreciated or a fix.