The Automatic Sync of Dynamic group depends upon the plan you have subscribed to.
Pro: auto-syncs every 4 hours.
Enterprise: auto-syncs every 1 hour.
Ultimate: auto-syncs every 15 minutes.
Ultra: auto-syncs every 5 minutes.
Apart from this, you can manually sync the device groups. To do this, select the desired groups from Manage > Device Groups, click on the ‘Actions’ button and choose the ‘Sync dynamic Groups’ to sync all dynamic groups.