As an aside, I don’t think you actually have fast internet - or whatever you are downloading doesn’t have any mirrors even remotely close to you.

Assuming the GB is Gibibytes (worst case scenario), that is 730,144 Megabits (not bytes). With a 100 Megabit connection (lower end of what most ISPs offer that I’ve seen and still call it “high-speed”) that should be done in about 2 hours. In 8 hours at 100 Mb speed you should be able to download over 300 Gigs of data.

85GB in 8-12 hours is somewhere between 17 and 25 Mbps, which would be stressed out by 1080p video streaming.