How to politely let someone know you are not interested in being friends with them without hurting their feelings

So I have an acquaintance that I met through a local social group who is persistent about hanging out more and getting to know me. There is nothing majorly wrong with this person and they are nice, but our personalities don’t vibe and they have a few red flags that I personally don’t want to deal with if I became friends with them. I’m fine with being social with them in a group setting, but I don’t want to hangout with them one on one outside of group settings. The other problem is they live in the same apartment complex as me. Every time they ask to do something I just say I’m busy, but I know that gets old and someone can’t be THAT busy. I’m getting to the age where I’m choosy about my friendships and time. Not trying to brag at all, but that’s where I’m at right now. I don’t want to hurt this person’s feelings by being blunt as we just don’t vibe, and they didn’t do anything wrong to me.