WIf you only want to process files that have the "Archive bit" on, and skip all other files, then you must set the RequiredFileAttributes property to xfaArchive.

If you only want to process files that have the "Hidden" or "System" attributes on, and skip all other files, then you must set the RequiredFileAttributes property to xfaHidden + xfaSystem.

But…

If you don't want to process files that have the "Archive bit" on, but you do want to process all other files, then you need to use the ExcludedFileAttributes property, not the RequiredFileAttributes property.