Error in installation

[Ax721]

i tried to install thru CentOS 7, but i get the below error message:

Enter the domain names separated by commas (example: google,youtube): intel.com sed: can't read /etc/nginx/sites-enabled/default: No such file or directory sed: can't read /root/smartSNI/nginx.conf: No such file or directory Saving debug log to /var/log/letsencrypt/letsencrypt.log The requested nginx plugin does not appear to be installed cp: cannot stat ‘/root/smartSNI/nginx.conf’: No such file or directory The SNI service is now active

what should i do?