Send extra fields to Zapier after PMPro checkout.

my_pmproz_after_checkout_data.php

<?php

// Copy from below here...

/*
 * Send extra fields to Zapier after PMPro checkout.
 */
function my_pmproz_after_checkout_data( $data, $user_id ) {
	// Assuming 'first_name' and 'last_name' are fields on your PMPro checkout page.
	if ( ! empty( $_REQUEST['first_name'] ) ) {
		$data['first_name'] = $_REQUEST['first_name'];
	}
	if ( ! empty( $_REQUEST['last_name'] ) ) {
		$data['last_name'] = $_REQUEST['last_name'];
	}
	return $data;
}
add_action( 'pmproz_after_checkout_data', 'my_pmproz_after_checkout_data', 10, 2 );