Advice or instructions for an ADHD late-bloomer on approaching people in real life?

I’m late diagnosed ADHD and high-functioning autism, and was very late on the dating game (my first date was when I was 23, and a senior in college). I’m mostly introverted but very outgoing when I’ve warmed up to a space/activity. I’m a fairly quirky and nerdy guy, but I tailor the intensity of that to the people I’m around.

Every person I’ve ever dated I met on an app, because I’m very uncomfortable approaching someone without knowing if they are both single and looking to date.

The general consensus from the comments I got on my dating profile were that the type of people I’m looking for aren’t going to be on apps, and I agree. Ren faires, book stores, game shops, those kinds of spaces have the people I’m looking for. But I can’t imagine walking up to people and striking up conversation unprompted and actually having a friendship start out of it, let alone any sort of romantic intent. There are just too many unknown variables that my brain muddles and I have no idea what’s appropriate or if I’ll make it awkward or if they’re even interested in talking etc. etc.

I’m also not comfortable flirting with someone I’ve just met unless they’ve explicitly said they’re comfortable with it, and will assuredly not notice if I’m being flirted with unless someone talks me.

I feel so lost doing anything besides apps. Does anyone have any advice, or hell, some kind of instructions on how to properly meet and ask people out in the real world? When is it appropriate to strike up a conversation, what do you open with, how to keep it going, how to tell if they’re interested, etc.