The credit asks for a Composite STC rating. This essentially means the transmission loss of the wall in addition to the transmission loss of the door, averaged based on their respective areas. So you won't need an STC 50 rated door assembly, but it may still be hard to achieve an STC 50 composite rating unless you have a large wall area with a high STC rating and a small, standard STC 35-40, door.
Question
Our project has small meeting rooms in an open-office plan. This situation appears to require an STC of 50. However, this level seems to be (unrealistically) high, especially considering the doors in the wall partition. STC 50 with a (closed) wall can be achieved, but even high STC doors won't achieve an STC of more than 45. Would this mean that the credit is not achievable?