Additional Study Information: This research is being done to study the effects, safety, and tolerability of the study drugs Nivolumab and Urelumab when given to people with advanced bladder cancer that has spread into the muscle tissue, also called Muscle-Invasive Urothelial Carcinoma of the Bladder (MIBC). Specifically, this research study will have participants either take Nivolumab in combination with Urelumab or Nivolumab alone.