Lemmy.ml currently (and probably for the forseeable future) doesn't allow the creation of new communities. You could ask the admin to create a community for you, but I can't say more beyond that. I don't know if that's okay or not, I don't have an account on lemmy.ml.
Another alternative is to create an account on another instances that allow new communities and create a community there.
I don't think contacting the admins is likely to help. I don't have the link handy, but the lemmy.ml admins recently posted about turning off community creation, and the general vibe was that as the founding instance of the threadiverse, lemmy.ml holds an unhealthy fraction of its communities. They're going to correct this by letting the rest of the instances catch up by hosting newly created communities.
So there would have to be a real good reason to host specifically on lemmy.ml, and there aren't very many such reasons that a non-admin would have.
Worth noting that this is the fediverse, you don’t need to be on the latest instances if you’re not fond of their moderation policies (such as inability to create your own community). You can always sign up on another instance that allows for such, and (as long as it is not doing something egregious like allowing illegal content thereby getting themselves de-federated), you can still interact with content on yet another instance (as shown here I am commenting from a personal instance).