Like many people said, Lauren got some stick on twitter not because of her social anxiety but the fact she was seemingly almost trying to not enjoy herself.
Even that Daniel she made friends with seemed to be getting fed up of the fact she was just seemingly trying to dislike everything. Like when she went on that bar crawl to 'try' it, she seemed to just be stood by herself making no attempt to actually enjoy herself, so then how is it a surprise when you don't? But then some of her flatmates, who will only ever be freshers once, decided to end their night early to make sure she got back OK. But instead of seeing that as a positive and feeling those around her cared, it was just more sulking and depressing twitter messages. I could perfectly understand why some people wouldn't want to share a flat with her, because when everything is trying to have fun and enjoy university she spent the whole week seemingly trying to drag people down rather than trying to have fun.
On freshers most people, even if they have social anxiety or similar, will at least usually try and have fun in some way. I think she got stick because it seemed like she was pro-actively trying to not have fun and moan during the beginning.