Your Job Board Token is the unique part of your board's URL on Greenhouse.
For example, Idealist's URL on Greenhouse is boards.greenhouse.io/idealist, so Idealist's Job Board Token is simply "idealist." To learn more about Job Board Tokens on Greenhouse please visit this Greenhouse Help Center article.
To learn more about integrating your organization's Greenhouse and Idealist account, please visit this Idealist Help Center article.