If you don’t have a service already set up for file transfers, I can suggest a couple of them that you can use at no charge.
youSENDit , that will require you to create a free account
or
wetransfer , that you can use whenever you need to without having to create an account with them.
For my daily-basis clients, I offer the use of T3Pro, Total Transcript Transfer, which was specifically created to meet the needs of court reporters, scopists, and proofreaders. Sharing files through T3Pro is not only AWESOME, but it’s faster, and safer, allowing both parties to keep track of all the details and times of transfers.