Jesus told Judas that he would betray him. Does this not conflict with mankind having free will and the ability to choose our own deeds?

No.

First, faulty premise. Jesus never told anyone that someone would “betray” him. He told the Twelve that one of them would hand him over.

Second. God handed Jesus over, and Jesus handed himself over. As God sent Jesus to serve Him, so Jesus sent Judas, and he sent him as his servant in order to hand himself over.

Third. Jesus did not coerce Judas, but he gave him a choice: “That which you do, do quickly.”

Judas could have refused to go. Judas could have given in to Satan, which entered into him and opposed those things of God which Jesus said should happen at Jerusalem.