You'll need a director identification number (director ID) if you’re
a director of a company registered with the Australian Securities and Investments Commission
a director of a corporation registered with the Office of the Registrar of Indigenous Corporations
planning to become a director in the next 12 months.
It’s a unique identifier you apply for once and keep forever.
https://www.ato.gov.au/Newsroom/smallbusiness/General/Are-you-a-director-/?sbnews20220620