b. The review by the planning board of a conditional use shall include any required site plan review pursuant to article 6 of this act. The time period for action by the planning board on conditional uses pursuant to subsection a. of this section shall apply to such site plan review. Failure of the planning board to act within the period prescribed shall constitute approval of the application and a certificate of the administrative officer as to the failure of the planning board to act shall be issued on request of the applicant, and it shall be sufficient in lieu of the written endorsement or other evidence of approval, herein required, and shall be so accepted by the county recording officer for purposes of filing subdivision plats. Whenever review or approval of the application by the county planning board is required by section 5 of P.L. 1968, c. 285 (C. 40:27-6.3), in the case of a subdivision, or section 8 of P.L. 1968, c. 285 (C. 40:27-6.6), in the case of a site plan, the municipal planning board shall condition any approval that it grants upon timely receipt of a favorable report on the application by the county planning board or approval by the county planning board by its failure to report thereon within the required time period.