I am trying to set up easycron
The username and password are for a WordPress user.  I would recommend setting up a user specifically for this purpose and don't use it for anything else.  

You will need to give the user the correct permissions: 


View all contacts
Access CiviCRM
Access CiviMail


Please see the documentation for more details: Scheduled jobs

You will need to set the site key in the civicrm.settings.php file - see: Site key