"Auto-Synced Files" is short for "Automatically synchronized files".
In the context of Flatly, a file is a CSV, XLSX (Excel) or Sheets (Google Sheets or Smartsheet) file.
Overview of a File
"Automatically" means Flatly replicates your business data into a flat file without you having to click on any button.
"Sync" is the act of replicating your business data as a file. Also called "copy" or "refresh".