If the site holds zip[s] named DYYMMDD.zip, this will get the latest one.

::==
@echo off > mydir.ftp
setLocal EnableDelayedExpansion

>> mydir.ftp echo o mysite.com
>> mydir.ftp echo username
>> mydir.ftp echo password
>> mydir.ftp echo cd mysite.com
>> mydir.ftp echo ls D*.zip
>> mydir.ftp echo bye

ftp -s:mydir.ftp > mydir.txt

for /f "tokens=* delims= " %%a in ('find ".zip" ^< mydir.txt ^| find /v "ls D*.zip" ^| sort') do (
set str=%%a
set latest=!str:~0,-1!
)

> getzip.ftp echo o mysite.com
>> getzip.ftp echo username
>> getzip.ftp echo password
>> getzip.ftp echo cd mysite.com
>> getzip.ftp echo bin
>> getzip.ftp echo get !latest!
>> getzip.ftp echo bye

ftp -s:getzip.ftp
::==

=====================================
If at first you don't succeed, you're about average.

M2