I promise, I know the worry/heart-ache that comes from watching a kid struggle to find friends. So I hope this isn't salt in a wound.
We sent our 16 y/o daughter to BYU Tennis Camp by herself. Her roommate was maybe a bit of a dud (on her phone whenever they were in their room), but our daughter really liked the tennis, activities, and other kids. I don't think she made any life-long friends, but she hung out with kids from Colorado, California, etc. and they all had fun. I think she exchanged texts with a couple of girls she spent more time with since camp ended, but not much beyond that. So, we were satisfied/happy that at least for the duration of camp she was getting to know other people and enjoying the friendships.
Overall, she loved it.