I never joined one.
But for the sake of mental health, depends on the utility or need.
If you want understanding, feel less alone, grieve whatever social woes, go to any autistic lead groups.
See if the sentiments and attitudes matches yours, same struggles and needs, similar circumstances and experiences.
If you want friends, go to an interest based groups regardless being an ND space but that would be better.
Preferably somewhere not toxic/sweaty/strict/elitist/predatory...
You can join one or two and both separately, join one and join another later...
And I'm not sure how frequent gaining both happens.
I have some doubts in autism groups facilitated by NTs.
Accounts tells me it's usually for kiddie types of socialization, which tend to be overall mismatching (the autistics you will meet might not be as communicative nor may match your developmental level/expected methods of socializing), awkward, or basically all-or-nothing depending on the dominant obsessions.
Unless, well, you're a desperate enough teenager and ended up talking to the NT adults there instead.