#Massive update download
4 messages · Page 1 of 1 (latest)
There was a major game update and patch 2 days ago and another small patch today, so if this is the first time you have been on in months, that is likely the reason. It will need to download all new updates and patches since your last login in order to play.
Assuming you don't play on Steam, there's also been a launcher update that makes it look as if you're redownloading most of the game but it's not actually downloading that much, just scanning files.
As Shintar already said, those 36gb aren't 36gb extra storage space required. It's the amount of data that's fixed/replaced/maybe a bit added