tl;dr Helps with Anxiety, and as a result, kind of helps eliminate some of the social awkwardness associated with ASD.
I've only smoked pot once but it did nothing to me. I don't think I did it right.
That's a fairly common occurrence for first-timers, don't worry.
And I would say that it definitely affects ASD individuals differently. I had tried it a few times in my teens and never really enjoyed it. I definitely got high, but at the time I was unable to understand why people would break the law and risk huge penalties (I was in Virginia at the time) for it.
Even during/after college, when I began smoking more frequently, it took me a very long while to fully relax and enjoy it. Often I would smoke too much and end up feeling super uncomfortable and out-of-control (usually after a major coughing fit) and I'd have to go isolate myself and calm down or I'd risk spiraling into a panic attack. My heart would pound out of my chest and I'd feel all shaky and wired like I'd just chugged a pot of coffee.
Over time I learned how to regulate my intake so as to not get "too high." It took a lot of passing on hits and playful chiding about being a lightweight (which was actually kind of hurtful, though unintentionally) before my tolerance reached a level where I could keep up.
Living in a place where it was still very illegal, I didn't have much of a choice in selection. Occasionally my guy would tell me he had a specific strain, but I had no way of knowing if he was telling the truth or trying to talk up his product. Most of the shit that we got was Sativa, which isn't the best for some people with Anxiety. It can cause the rapid heartbeat and "upper" feeling that I found so uncomfortable and worrying.
Still, I found the benefits of marijuana for treating my Anxiety outweighed the drawbacks so much that I moved halfway across the United States to Colorado, where I can walk down to the store and buy just about any strain I could ever imagine. And as I found out, the strains matter a lot. I've experimented with pure indicas/sativas and a lot of various hybrids, and come to learn that generally, indica-dominant hybrid strains are the best for me. Weed's still weed, but when you live in a place where it's legal you get the luxury of being picky.
Being legal also removes a lot of the anxiety associated with being high in public or worrying about getting caught in possession and going to jail or having to pay massive fines. For people without anxiety that may seem like a non-issue, but it was always in the back of my mind that every knock on the door could be the cops. Now that I'm in Colorado I can rip a bong sitting outside on my front porch and nobody even bats an eye. I recently changed jobs and my new boss and owner of the company just straight-up asked me if I smoked, and didn't care a bit that I do. Now I don't feel like I'm keeping some kind of secret, which is nice.
However, I wouldn't say that it really treats ASD. For me, it tends to enhance the good aspects (creativity, focus, reasoning) and dull the bad ones, mostly just by getting rid of the anxiety. I don't know if it's the weed itself or if the gradual process of acclimating myself and my brain to the feeling of being high was some kind of pseudo-therapy, but it's worked.
I now use marijuana daily for both medication and recreation. It works great for de-stressing after work, getting rid of migraines, and being more emotionally open and accessible to my friends. It lets me enjoy visual/aural media at a new level, and makes tedious tasks that I would normally procrastinate on (like chores and cleaning) easy and kinda enjoyable. And it works great to turn off that late-night deluge of thoughts that used to keep me worrying until the wee hours of the morning.
Ultimately the best piece of advice I can give is to start with small hits, relax, learn to ignore the anxiety voice in your head, and enjoy the high. If you can get it, try to find some Indica or some hybrid bud.
If you're in a state with a Medical Marijuana program, you might be able to acquire tinctures, edibles, trans-dermal creams, vape pens, and other concentrates, each of which will produce a slightly different high. Vaporization rather than smoking your flowers will also produce a different high, and is more clandestine, if getting caught is of serious concern. If you're worried about coughing fits (I was, because they draw so much attention) vapor is also much less harsh, and there are a multitude of ways to cool and filter smoke.
And while this is just anecdotal, I've noticed that in the same way that I learned to ignore the anxiety in my head while high, I'm able to ignore it better while I'm sober as well, which I hadn't been able to do until I began smoking.