This feature is available with Enterprise and Business plans. See Pricing plans for more details.
Groups allow you to organise multiple Snyk organisations which can be used to reflect teams or products.
If your company currently does not have any group admins you will need to ask Snyk support to promote at least one user.
Once you have one group admin, they can promote other users to also become group admins.
To do this navigate to your group overview > settings > members and click the add administrators buttons.