There is a single page for registration and Login - both using the Sign In with linkedIn service. Any user with a LinkedIn account can click the button to sign in. If this is your first time visiting HORIZON PPM you'll be asked to register at the sign up page. Existing users will be authenticated and logged straight in.
If you have logged out of LinkedIn you'll need to provide your LinkedIn username and password - as prompted by LinkedIn themselves. You do not need to share these details with us.