When you are invited to an FSP account, they you will receive an invitation email with the subject line "Invitation for Online Access". On this email, you just need to click the "Click here to Sign up or Sign in" hyperlink.
Next, if the you have never used FSP before, you just need to fill out the required fields and select signup.
If you already have used FSP before, and have an FSP login, you just need to select "Log In" at the top.
If you already have an FSP account and you fill out the form using the same email as your FSP account you already have, you will get the following error message. If this happens, you just need to select the Log in button.