Yes .RAR files should be fine.
Upload the zip file to the ftp server
ftp://ftp.avast.com/incoming:
- Using Internet Explorer, Connect to the link and drag the file into the Right pane and drop it, that starts the upload, you don't have read access to this folder, so you won't be able to see it once uploaded.
Or
Upload it using the Run command-line in Windows: Windows Key + R (to get the run box), copy and paste this
explorer ftp://ftp.avast.com/incoming
and drag the file into the window, from another explorer window.