The facility administrator or the administrator's authorized, qualified designee may admit a person for whom a proper request for voluntary inpatient or outpatient services is filed if the administrator or the designee determines:
(1) from a preliminary examination that the person has symptoms of mental illness and will benefit from the inpatient or outpatient services;
(2) that the person has been informed of the person's rights as a voluntary patient; and
(3) that the admission was voluntarily agreed to:
(A) by the person, if the person is 16 years of age or older; or
(B) by the person's parent, managing conservator, or guardian, if the person is younger than 18 years of age.