I’m not sure if I understand correctly, but I’m assuming that you want to copy a file from a given path to the Downloads folder, and that the given path is stored in the fileRef
variable as alias (see end of your script).
So, to copy it, this should work:
set destDir to path to downloads folder from user domain
tell application "Finder"
duplicate fileRef to destDir replacing no exact copy no
end tell
Use replacing yes
if you want to overwrite existing files in the Downloads folder without warning.