How do I tell if a group of people I just met likes me? How can I tell if they’re just being nice?

To clear a few things up, I am indeed autistic and have had instances where I thought social interactions were going well just to have that person never speak to me again. I met a bunch of new people at an event yesterday and I think it went well but again I can't always tell. How do I know if a group of people generally likes me from the first impression/wants to include me and is not being fake nice?