Did Christ teach you had to believe in the Assumption of His Mother to get to heaven? Rome does.
Did Christ teach that the leader of the Catholic church in Rome would be infallible when speaking in certain circumstances and that believing this was necessary in order to attain salvation? Rome does.
Did Christ or the Holy Spirit through the Apostle John teach the myriad dogmatic positions of the Roman Catholic Church and require them to believe to attain eternal life? Rome does.
Your question: “Did Christ teach you had to believe in the Assumption of His Mother to get to heaven?”
Yes He did through His Church - the Catholic Church.
http://www.cuf.org/2005/02/that-they-may-all-be-one-the-difference-the-church-makes/