Go to lti-ri.imsglobal.org and click "Login" at the top right of the screen. This will initiate a new login into your account at imsglobal.org. Once you login, you will be redirected to the One Roster Reference Implementation.
Once on that page, click the button that says "Use [Your Team]". If you don't see a team you can create a new one here, and then click the "Use [Your Team]" button to switch to that team. At that point, your current Team for your local session is active for all Reference Implementations.
Now, return to lti-ri.imsglobal.org, and you should see your selected Team in the top right corner where the Login/Logout links appear. When you see that team on your LTI Reference Implementation, you can now claim the Platforms/Tools as your own (and they will disappear for all others not in your team.)