This was me, as well. I wasn’t on the spectrum, but I was a little, skinny, unathletic kid, who had absolutely zero interest in sports until I was about 12. My dad tried to teach me how to hit a baseball, how to shoot a basketball, etc., but I was both clumsy at it, and not really interested in it (my disinterest heightened by also recognizing that I was really bad at it). Also, being a bookish, nerdy kid, I was far happier being at home, reading, playing with my model trains, or building models.
So, yeah, it made being forced to participate (like during gym class) just miserable. When I was 10, my father enrolled me in taekwondo at a local dojo; this had the advantage of (a) helping me learn some physical/athletic skills, and (b) letting me do so without being subjected to the teasing of my classmates.
(When I was in college, and took a semester of fencing, I started out terrible at it, but got better late in the semester. At the end of the semester, the coach noted how far I’d come along, and then asked me, "tell me – how long did it take you to learn how to ride a bike? My answer was “an entire summer,” and he nodded knowingly. “Kenobi, you are what I call a ‘slow physical learner’ – it just takes you longer than most people to learn and master a physical skill. Don’t feel badly about it; my son is that way, and he’s now an Olympic fencer…it just took him longer.”)
Anyway…yeah, team sports, esp. for kids, can be great, but not every kid is going to be good at it, at all, and some just don’t care (and being among your peers, who are going to tease you about being bad at it, is absolutely a problem). Keep encouraging your son to find something active that he might enjoy.