While you're signed in as an Admin, navigate to the Configuration tab of Settings. Choose Applications from the left side and scroll down to the FTP section. Click to Enable FTP and choose the types of users that will be allowed to utilize the feature (Admins or Admins & Power Users).
Then, select the FTP, FTPES, or SFTP checkboxes and click Save.
If your users received one of the error messages below, it means that the service has not been enabled for the domain or for their user type. An Administrator will need to enable it using the steps above.
SFTP access is not available to this user. Contact your account Administrator for details.
SFTP access is not available to this domain. Contact your account Administrator for details.