stuck on synchronize command, plus want to do more...

So I (and ChatGTP) wrote this little script file but not sure if it is working, and I know it does not do everything I want yet. ChatGTP helped on it and I think it is wrong.
What I would like to do is for it to compare what I have on my local drive with what is on the site, if I do not have what is on the site, DL it. I'm only interested in DLing files, not uploading. Optimally I would like to check for criteria check so I think I need to add "-criteria=<time, size, checksum>" but not sure where. On the main app I have it set to 2 concurrent transfers, but if I change that, this changed. I would like for bat file run to stay that way with 2 concurrent transfers.

Also, any advantage to changing any of the other parameters? The files are going to be 20MB to 20GB.

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Script file:

open Skyrem_Edu
option batch on
option confirm off
option log "C:\Program Files (x86)\WinSCP\LogFile\winscp_log.txt"

synchronize local "X:\Files\V\S" "/files/V/S" -mirror -neweronly

close
exit
Bat file:
@echo off
"C:\Program Files (x86)\WinSCP\WinSCP.com" /script="X:\Files\V\Educational\SFTP_Educational_sync_script.txt"