(ii) Designer shall submit the detail plan and get approved by Designer for the Showroom in advance 45 days before the Collection.

-> News shall submit a detailed plan for the Showroom to be subjected to Designer's approval, 45 days in advance of the Collection.
(앞에서 plan이 특별히 거론되었다면 the plan)

Designer shall pay the Showroom Fee in advance for each month provided that News’ plan for the Showroom get approved by Designer.

-> Designer shall pay the Showroom Fee in advance of each month, provided the plan submitted by News is approved by Designer.

Designer cannot delay approval without reasonable reason

-> Designer cannot delay giving approval (beyond a reasonable point in time, or) without due reason.
(괄호 안은 그냥 넣어본 겁니다.)

Distributed Marketing Materials and Expenses for Additional Services shall be paid by Designer after getting approved by Designer in advance.

-> 이 부분 두 디자이너 중 전자는 News인가요?