The first time you join you will be prompted to sign exchange agreements. These are agreements with NYSE and NASDAQ. You are declaring yourself as a non-professional trader (a trader who is not licenced to be a stock broker by the SEC). You will be asked to enter your username, which is the same one you just used to login to the platform. It will begin with WAR. Once you complete these agreements, you can log back into the platform.
Short Signing Agreements Video