Whenever you enter a new (sub-)culture, you have to learn the social norms. Some people have an easier time, others have a harder time. There's not much advice we can give you, since every culture is different. Some value privacy, others openness and honesty. Some communicate stuff via head nods, others by how far you stand away, and others by pitching the tone of their voices.

You will learn too, but it will take lots of exposure and trying. Some people will dislike you for not understanding, others will be forgiving. How much you should make allowances and whether it makes sense to tell them that you are autistic depends on their specific culture and personalities. So, uh, good luck.

note: (sub-)culture here does not mean only the nation you're in, but it can change group-to-group. Essentially it's the vibe that a group has.