When editing the users within your team you have the option to assign 3 different roles to them.
Member is the lowest role within ServerAuth, a user with this role has access to manage their own SSH Keys and view the servers within your team. They do not have access to create servers or grant / revoke access to servers. This role will likely be used for most of your team.
Manager is the next role up, a user with this role has access to everything the Member does but with the added permissions of being able to invite new people to the team, create servers and grant / revoke access to the servers within your team. This role will be best suited to the team leaders within your organisation.
Admin is the highest role you can assign someone, this user has access to everything the Manager does but with the added permissions of managing the billing information, the subscription plan and the ability to manage Team details. When creating a team, you are automatically given the role of Admin.
Please Note: While Managers can invite new people and manage the existing team, they cannot grant an Admin role to a user, only existing Admins can set a user as an Admin.