How do I troubleshoot YouTube error code 403 Smart Downloads?

Troubleshooting steps include: 1) Verify your YouTube Premium subscription is active and valid through the Google Play Store or YouTube website. 2) Check your payment information for accuracy and ensure your payment method is up-to-date. 3) Try clearing your browser's cache and cookies. 4) Restart your device (phone, tablet, computer). 5) If using the YouTube app, update it to the latest version. 6) Try logging out and logging back into your Google account. 7) Contact YouTube support if the issue persists.