To allow third-party cookies on a Mac, open the browser settings first. In Safari, click Safari > Settings > Privacy, then uncheck “Prevent cross-site tracking” and make sure “Block all cookies” is disabled. In Google Chrome, go to Settings > Privacy and Security > Third-party cookies, then choose “Allow third-party cookies.” For Mozilla Firefox, open Settings > Privacy & Security and set Enhanced Tracking Protection to “Standard.” Restart the browser afterward to ensure the changes take effect.