You can route/ftp zip file using webMethods public FTP services out of box.
WmPublic/pub.client.ftp (package/folder services) and set the service inputs per the documentation (BIS userguide)
public services to use FTP transmission are
ftp:login (ftp server)
ftp:cd (remote directory)
ftp:put (map the local file(full path and remote file (full paths with .zip) or you need to use getFile (loadAs bytes) and then map it to the content object in the put service with naming remote file name) with transferType = binary
ftp:logout (ftp server)
Ofcourse always put a Error Handling framework to handle all FTP reason code/failures.
HTH,
RMG
#webmethods-Protocol-and-Transport#webMethods#Integration-Server-and-ESB