Answer
I say, and with God's success: Zakat is not obligatory on the disbeliever; because Islam is a condition for the obligation of zakat; as it is a pure act of worship; being one of the pillars of religion, and the disbeliever is not addressed, so it is not obligatory upon him just as it is not obligatory upon him regarding the other pillars of religion, as stated in Tabyin al-Haqaiq 1: 252, and God knows best.