There you can edit the board on this site page. Type a board name and select the SharePoint task list from a source site that contains the data you will display on the Kanban board. Click on “List” field and choose the required list from dropdown menu.
Then you must select fields that contain task title and assigned user.
Note: The list must have the choice field and user field. If the source list/library does not contain the fields of the choice type, it cannot be used as a data source for Virto Kanban Board Web part.