As stated in the full calendar license page Metronic only includes the free version of the Full calendar plugin. The Scheduler extension of Fullcalendar is a premium plugin and can not be included in Metronic due to license limitations.
However you can purchase Scheduler and use it with Metronic by including it as an external plugin but the style of Scheduler will not match Metronic style and you will need to customize it if needed.