Hi Alex,
We are still in the process of updating the documentation for PayPlans 4.0.
For cronjobs, there are 2 ways to setup, automated cronjob and scheduled server cronjobs.
Automated cronjob(from settings) - runs every time PayPlans is accessed in the frontend. Used as a last resort(if setting up scheduled server cronjob is not possible) and not recommended as it depends on site traffic.
Scheduled server cronjob - You have to setup a scheduled cronjob on your server along with a period on which it runs automatically. This is the recommended approach to setup cronjob for PayPlans. The url to run cronjob on PayPlans is as below.
site.com/index.php?option=com_payplans&view=cron&task=trigger