In addition to two formal outfits (for the Sangeet and Wedding + Reception) and a cocktail outfit for the welcome drinks, bring whatever you would need to enjoy your time at an all-inclusive in Cancun! Weather is generally warm (in the high 70s and 80s) so shorts, sandals, sunscreen, and swimwear is recommended. There will also be time for excursions (such as ziplining or exploring natural pools) so bring appropriate clothing for that as well if you're interested.
See this outfit guide for more details! https://tr.ee/ac_what_to_wear