Add a cron job by executing below command in linux shell. If you are using the Cpanel or Vesta Panel then follow a guide from here to setup a cron job.

crontab -e * * * * * php -q "/home/u287166658/domains/smsprohub.com/public_html/cron.php" >/dev/null 2>&1

You can find frequently asked questions from here.

If FAQs doesn't resolve the issue you are experiencing then you can open a support ticket from here.