The following controls are available at the bottom of the Preview dialog.
OK button - Saves your initial run options, asks if you want to start the task (usually, "Yes") and asks if you want to enable the task to allow the scheduler to run it automatically.
Change Initial Run Options button - Allows you to change your initial run options to include/exclude more files from the initial copy step. This button will be visible on the Preview page only until you run the task for the first time. See the "Initial Run Options" section in the "Synchronization - Add New..." documentation for more information about sync task initial run options.
Refresh button - Refreshes the preview page with more recent information.
Cancel button - Closes the preview window and leaves your new synchronization task disabled. Before enabling or running your new task, you should use the "preview" option to make sure all connectivity is in place and that synchronization will be occurring the way you intend it to happen.
Show "no action" entries" checkbox - Shows or hides any entries marked with an action of "- none -'".