A Workflow Job is essentially set up the same way as any other job. Working with FTP Processes depends on the Activity that is used and the operation being performed. 

Create a Job using the Workflow Execution Method. In the Job Source, drag-and-drop the appropriate FTPSession Activity, be sure to fill out the forms on the right-hand side as shown. Strings are treated as VBExpression and must be wrapped in quotes.

Drag related FTP Activities into the FTPSession Activity as shown.

As an example, if files need to be deleted after downloading, add the FileTransferSessionDelete activity, and fill out the appropriate information on the right.

The file mask for RemotePath should match each other in both FileTransferSessionDownload and FileTransferSessionDelete. A Workflow Variable can also be created to reference the files.