I didn't, the club had a discord server so I already knew who she was. But that is a fair concern, and I have asked people for numbers/socials/etc occasionally. This struggle is not at all unique to PWS and something that pretty much everybody starts out deathly afraid of. Realizing this helped me a bit on its own. As for how to do it, the answer really is just to do it. "You're cool, can I have your number?" Its really as simple as that. I know this is kind of a hard pill to swallow and I still feel like a moron doing it every time, but again we need to realize that everybody does it this way, it's the only way it can be done. You basically just need to give yourself exposure therapy to warm up to the idea of just doing it. It takes a hell of a lot of mental effort but you'll get there. But either way definitely get to know them just a little bit first. You don't have to be best buds, but hang around in some conversations and pipe in here and there so she at least knows you're not a complete weirdo. I did forget one important piece, the first time I met my girlfriend I was absolutely plastered. Liquid courage really is a thing. Don't use it as a crutch, but it can definitely help loosen you up a bit. I was hitting on her pretty heavily. She pursued me after the fact because I really thought I made a total ass of myself that night and assumed she wanted nothing to do with me. But I think even if I said nothing the entire time she still might've pursued me.