You will need to be either an Owner or Administrator to access user management feature within your oak9 tenant.
User management will enable you to manage who has access to your oak9 tenant and what they are able to access. The document will help you,
You can access the User Management capability by selecting your name from the top nav menu and selecting "Manage Users" (see below). You will need to be either an Administrator or an Owner to access the user management.
You can invite new user(s) by clicking the "Invite User" button and entering their email address. Once you select and Save, we will send an email invite to those users. The user invite link expires in 15 minutes.
You can update a user's role by selecting the role drop down.
You can remove users by hitting the trash icon next to their name