Let coworkers join automatically
People with a matching company email can find and join your org without an invite.
If someone signs up with a verified email at your company's domain, they can find your organization and join it rather than accidentally starting a second one.
Organization · Joining
It only ever applies to real company domains. Personal email domains are never joinable this way, so nobody joins your org just because they use the same email provider.
This and an email invite are the two ways into an org. There is no shareable join link.
NoteAn owner or admin can switch domain join off in Settings, in the organization section, if you'd rather approve every person by invite.
Still stuck? Ask your Chief of Staff, or contact support.