Adam Clarke on Acts 20:6

Days of unleavened bread - The seven days of the passover, in which they ate unleavened bread. See the account of this festival in the notes on Exodus 12:1-51 (note). It is evident, from the manner in which St. Luke writes here, that he had not been with St. Paul since the time he accompanied him to Philippi, Act 16:10-12; but he now embarks at Philippi with the apostle, and accompanies him to Troas, and continues with him through the rest of his journey.

To Troas in five days - So long they were making this voyage from Philippi, being obliged to keep always by the coast, and in sight of the land; for the magnetic needle was not yet known. See the situation of these places upon the map.