The Mixpanel Community is a place where users can share ideas, ask questions, and learn how to use Mixpanel. However, the knowledge sources provided do not specify a direct method to invite someone to the Mixpanel Community. It seems that users can join the community by visiting the community page. You can share the link to the Mixpanel Community with the person you want to invite and they can join from there. Here is the link: Mixpanel Community.
Please note that there are guidelines for participating in the Mixpanel Community, such as identifying yourself, not creating multiple accounts, keeping discussions clean, and not posting spam or selling anything. You can read more about these guidelines here.