Hello and welcome to the forum,
Which server does not have an ftp service? The mainframe or the remote?
If the mainframe does have an ftp service, the remote can connect via the ftp client (which is part of every tcp/ip product i've used) and download the file. If the remote system has an ftp service, ftp may be run in batch to "send" the file from the mainframe to the remote.
There are other ways to transfer data from a mainframe to a remote including NDM (Connect Direct), 3270 file transfer, and an old method called IND$FILE. You would need to talk with your network support people to learn which might be available on the system.
Hope this helps,