To access an FTP via macOS X's Finder application, first you will need to make sure File Sharing is enabled.
Go to the Apple menu > System Preferences > Sharing
Checkmark the option for File Sharing
Once that is enabled, open Finder, and click on the Go menu option, and find Connect to Server. Or, you can press ⌘ + K on your keyboard to bring up the Connect to Server prompt.
On this Connect to Server prompt is where you will enter the FTP URL provided to you via email.
Once entered, press Connect and Finder will open the folder, displaying your MARC files.
Once accessed, you can also navigate to the sidebar of the Finder, under Locations and access the FTP folder there.
If you have any further questions, please contact us.