An Organisation Admin is a user who has an Admin Engagement with an organisation. This grants them the power to do the following (and more):
Manage engaged users (including inviting new users to engage and ending existing engagements)
Create and manage organisational templates
Generate aggregate reports of engaged users' assessments
If you are an organisation admin, you can access the Admin Console from the app menu. This will open a new tab. Note that the Admin Console is optimised for desktop use.