The Auto Export option when it's enabled exports the selected artboard whenever you make a change to the artboard.
Use Auto Export with Auto Refresh to see changes live.
The Auto Export option is only available in the Web Export panel.
When you first enable this option it will prompt you to select the folder that you want to export to. Using Auto Export will use the options you have selected in the Export Artboard dialog.
After you select the folder the artboard will be exported a message and a few new options are available.
The export message is automatically removed after a few seconds.
When Auto Export is enabled anytime you make a change the selected artboard will be exported.
If you select an element on another artboard that artboard will be selected.
copy link copies the URL of the exported web page to the clipboard
server link appears when you define a server. When you click on it it will open the link in a browser.
If you do not have a server value set then the server link is not created.
The url link defines the path to the exported HTML page. When you click on it it will open a link to the browser. If you are using Windows this opens a remote page due to a limitation.