@Grandmomma you shouldn't join a FC on a whim. I would be especially wary of FC's that auto invite members or accept anyone asking to join. People are different have different goals and interests and personalities. Blind auto invites increase the odds of clashes a lot more than at least some research.
That's good advice. I've found that guilds doing mass invites are almost universally awful.
As a rule when you're looking for a guild (or FC, or whatever term you want), you're looking for a group of players with similar goals. Guilds are usually used for organized gameplay, whether that means endgame content, or leveling content, or pvp, or coordinated knitting.
XIV actually has a small advantage in this area, because it also has linkshells. Linkshells can fill the role of a purely social environment just fine. And in fact, that's exactly what they're for. FCs are a bit more directed at gameplay goals.