You received the link because the client is a minor whose care needs a parent or legal guardian to authorize it. You'll review and sign the consent on their behalf — the same quick steps (read, type your name, agree, sign). When you finish, you'll get a confirmation that nothing else is needed.
Whether a young person can sign for themselves or needs a guardian depends on their age and their state; the platform sets that automatically. For questions about the care itself, your child's therapist is the best person to ask.