Does your DD feel that being and introvert is an issue for her?
I am a massive introvert who can pretend adequate social skills.
Uni at 17 was horrific for me - I felt that I should be pushing myself to make friends, that liking my own company was being a failure, not liking parties was a failure, not having a huge circle of friends was a failure. I put a huge amount of pressure on myself to be "normal" and that really wasn't good for me.
20 years later and still introverted, but I know it is ok to not party, it is ok to like my own company, it is ok to not "hang out" with other people. Uni this time round is a hell of a lot less stressful.
I'm a lomg-windsd way I'm saying that telling your daughter things like "you will be really isolated" like it's a bad thing, or "you will make lots of friends" like not making friends would be a bad thing will pile the pressure on her.
Listen to your daughter and don't tell her what she is feeling is wrong. If she doesn't want to share accommodation at uni she doesn't have to (finances permitting - though she may have to be in a building with other people)
People are in your face the whole time at uni, and it is very hard to escape. Listen to your daughter when she says she needs her own space.