Cron Jobs are not 'automatically' setup during the UNA installation. You would need to login to your cPanel/Plesk backend of your server to set that up. You can ask your webhost for assistance if you do not know how to set it up yourself. To know what cron job command you need, you can go into the Studio of UNA > Click Dashboard > Click the drop down error at Host Tool and do a server audit. Then look for the area of Cron jobs

You should see something like this (Your actual command may look slightly different - need this to be a single line):

*    *    *    *    *    /opt/plesk/php/7.1/bin/php -q /var/www/vhosts/yourwebsite.com/httpdocs/periodic/cron.php