You have received an invitation email with a link to register. When clicking the 'Register Now' link you will then be taken to the log-in screen and asked to fill in the details, once you have done that you will be taken to a dashboard with an alert asking you to accept the invitation. Click the ‘Accept’ button to successfully complete the registration.
Note: If you do not have the Safety and Accounts contact, they can be left blank when you are registering. You should be able to fill in the details when they're available using this guide.