This summary is not the rule. The rule text controls.
If you have the right to keep certain information private during a court case, your lawyer can speak up and claim that right for you. You don't have to be the one to say it out loud in court. Your attorney can do it on your behalf.
The court will automatically assume your lawyer has the authority to claim this privilege for you. This means nobody has to prove that the lawyer is allowed to do this. If someone disagrees and thinks the lawyer doesn't actually have this authority, they would need to bring forward evidence to challenge it. Until that happens, the court accepts that the lawyer can protect your privileged information just as well as you could yourself.
