There you can create a new board. Type your board name and select the SharePoint task list from a source site, which contains the data you will display on the Kanban board. Click on “List” field and choose the required list from dropdown menu.
Then you need to 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 Add-in.