Fatalism or free choice?

In Acts 21 the Holy Spirit plainly told Paul on more than one occasion through other people not to go to Jerusalem. Paul did not challenge that these messages were from God. Paul went to Jerusalem anyway.

In Jerusalem Paul took a vow and was planning on a sacrifice – very contrary to what he had been teaching. He was in the wrong place with the wrong people. (Who is the β€œthey” of 21:20?)