feat(pay): enforce VIP free-download daily quota like zibll

inc/classes/class-aksrt-content-visibility.php

@@ -171,6 +171,14 @@ class AKSRT_Content_Visibility {
             ]);
         }
 
+        // Zibll daily free-download quota.
+        if ($cost <= 0 && function_exists('aksrt_check_free_download_quota')) {
+            $quota = aksrt_check_free_download_quota($uid, $cost);
+            if (is_wp_error($quota)) {
+                return $quota;
+            }
+        }
+
         if (!empty($paid_settings['download_credit']) && $cost > 0) {
             $balance = class_exists('AKSRT_Credits') ? AKSRT_Credits::balance($uid) : 0;
             if ($balance < $cost) {