The organization administrator will send you an invite. When you receive, click on Accept Invite and log in to your existing account. Please be sure to accept ALL the invites if you are an admin to several groups.

If you didn't receive the invites, you can go directly to the website, log in, and check if you have any pending invites by clicking My Requests in the blue header.

Once you have accepted the request, you will then be able to access your member's records on the organization dashboard.