In the listening, you musts add 'am' for 'in the morning' and 'pm' for 'in the afternoon/evening' if that information is given. If you use the 24-hour clock, then you cannot use 'am' or 'pm'. Here, 16.00 (without pm) would have been correct. You can choose to write the time out in full, but be careful of the spelling. This candidate could have just written 4.00 pm instead.