Files.com operates three types of FTP integrations.
Files.com itself can operate as an inbound FTP server, allowing you and your users to connect to your Files.com account via FTP. This allows you to use FTP to access any portion of your Files.com account, even folders that are syncing to other providers, such as Dropbox, Box, Amazon S3, etc.
Secondly, you can Mount an external FTP site directly into Files.com as a folder. Files.com acts as an FTP Client in this context, making that FTP site available via the Files.com web interface, API, SDKs, and even other inbound FTP connections.
Third, you can configure a scheduled Sync, where Files.com will synchronize its copy of a folder or folders on a one-way or two-way basis with the external FTP server.
This integration requires Files.com's Enterprise Connectivity Addon, which is included for free on the Premier or Enterprise plan.