You may be able to set up the cron job here, but you will need to make some changes to the command to make it work.
The instructions provided by your website provide a system command to use. However, our Cron Jobs are technically “web crons”, meaning they call a URL on your website. You can’t use system commands with our cron jobs.
Give that the script is called runcrons.php, you should be able to trigger it with our cron jobs by providing the URLruncrons.php. The rest of the command provided are just boilerplate to make it work as a system cron.
Also, I strongly recommend to use the Cron Jobs tool in the client area, not in the control panel. The scheduling on that one is much more predictable and it logs the output of the cron jobs so you can see when it ran and what it did.