Zac began his career in Virginia before moving on to Selects Academy in South Kent, CT where he played for both the 16U and 18U teams. His strong play landed him a spot in the USHL for the 2018-19 season with the Tri-City Storm where he recorded 52 points in 55 games tying him for second in league scoring by a defenseman. Following the season, the New York Rangers selected Zac in the 3rd round of the NHL Entry Draft. Zac began his collegiate career the following season with UMass leading all minutemen defensemen in scoring as a freshman. He was selected to the US World Junior Hockey Championship Team in the same season. Zac returned to UMass in 2021-22 for his sophomore season where he helped the Minutemen win an NCAA National Championship. Following the season, Zac signed his entry-level contract with the New York Rangers and made his NHL debut on April 22, 2021. He recorded his first NHL point two games later assisting on a goal against the Buffalo Sabres. On June 16, 2023, the New York Rangers re-signed Zac to a two-year deal.