The thing is, autism can co-exist with other conditions that don't necessarily correlate with it. We have to remember that everyone is an individual and, as such, different people will have a variety of traits that have nothing to do with autism. Autism is the way a person's brain is wired and forms a backdrop to the rest of their psychological profile. It's like saying someone is good looking, so they must also have this or that - it's just one aspect of a person. You can be extrovert, introvert or ambivert and be autistic. Or, you can have a high, average, or low IQ and be autistic, etc.
One of the central problems for autistic people is the difficulty in understanding social interactions like body language, empathy, use of language, etc. It's hard for the autistic person to place themselves into another's shoes which means making the right kind of responses difficult. Also, the autistic tends to take things literally leading to misunderstandings and awkwardness in social exchanges.