Preheat an air fryer to 320 degrees F (160 degrees C) for 10 minutes. Cut a piece of parchment paper to fit the air fryer basket, leaving 1 inch on each side to use as handles.
Mix coconut, condensed milk, salt, and vanilla together in a large bowl.
Beat egg whites in a medium bowl with an electric mixer with a whisk attachment on medium-high speed until stiff peaks almost form, about 90 seconds. Fold egg whites into the coconut mixture.
Working in batches, spoon level tablespoons of the coconut mixture into rounds and place on the parchment paper, about 6 at time. Carefully transfer the parchment with coconut rounds into the air fryer basket.
Cook until golden brown and set, 9 to 10 minutes. Remove parchment from basket, transfer macaroons to a wire rack, and repeat the process with remaining coconut mixture using the same piece of parchment paper.
Microwave chocolate in a medium microwave-safe bowl on high power for 30 seconds, then stir. Continue microwaving and stirring in 30 second increments, until melted and smooth, about 90 seconds total.
Dip flat bottoms of macaroons into melted chocolate and transfer to a parchment-lined baking sheet to set. Let rest until chocolate firms, about 30 minutes.