As he approached Jerusalem, he sent two disciples, maybe Peter and John, to get the donkey for him to ride. He had made prior arrangement for the use of a donkey and the room.
In both instances Jesus and the man had some understanding and
if it wasn't the same man, we know Jesus may have had many acquaintances that are not mentioned in the Bible. I would like to know who they were and how he affected their lives.
Sometimes the Bible writers were very sparing with information. I guess that's why preachers build stories or parables or guesses that aren't substantiated.
Jesus has all the plans made for how the week would go. He did not question or halt in this demanding time. During the three or four days from the going to Jerusalem he seemed to teach with great fervor. It was more hurried than the preaching in the fields or by the sea shore. Sometimes the parables regarded the Pharisees and the Temple. Sometimes they were related to the pressure mounting against him. He wanted his disciples to be prepared for the mission. He stressed the need for watchfulness.
Finally he wanted to share the Passover with them. He wanted them to have this experience and to be able to see it as a source of strength. They would need this reassurance and support. He knew they would be scattered and isolated, and this was his last chance to form them into a united group. It was all he could do.