The Worklogger custom field can only be used in a workflow transition screen. You can not use this custom field when creating or editing an issue.
The Worklogger custom field must be used in conjunction with the Worklogger Validator
What is it?
This custom field is used to allow a user to log work in a workflow Transition. Please see Log Work on Workflow Transition for more details.
Configure the Worklogger Custom Field
Add a Worklogger Custom Field For more information on adding custom fields in jira, please see JIRA: Adding Custom fields
Select a name and an optional description for the custom field.
Associate the custom field to the screen on which you want it to appear. For more information on adding a screen to jira, please see JIRA: Defining a Screen