Organisation Codes are only available for paid subscribers, and can be used to add additional users to your account (Core Subscribers will have the ability to add up to 5 users, and Enterprise Subscribers can add up to 10 users). To find your organisation code, click on your name on the top right corner of the page and then select "User Management". Your organisation code will then be displayed.You can provide this to any other people in your organisation who have free accounts so that they can be associated with your organisation's paid subscription.