Expected End Date for employee onboarding missing

I cannot submit the employee onboarding. The error message is: “Error: Value missing for Task: Expected End Date”

Entering the date of joining does not help. I don’t see any other date I can enter. Where can I enter the end date?

While reading the documentation, I noticed that neither the onboarding template nor the Employee Onboarding Doctype gives me the option to schedule the Onboarding Activities by specifying the Begin On (Days) and the Duration (in Days). Maybe this is the issue? If yes how to correct it?

I use version 13.