Downloading file with Swiftydropbox

Thank you.  The problem is that I would not know the filepath of a user's selected file.  In the code below, what line is supposed to trigger the display of the user's files so that the user can tap on a file and return that path to my app?

// Download to URL
        let fileManager = FileManager.default
        let directoryURL = fileManager.urls(for: .documentDirectory, in: .userDomainMask)[0]
        let destURL = directoryURL.appendingPathComponent("/Documents/RamKolText2.txt")
        let destination: (URL, HTTPURLResponse) -> URL = { temporaryURL, response in
            return destURL
        }
        client.files.download(path: "/Documents/RamKolText2.txt", overwrite: true, destination: destination)
            .response { response, error in
                if let response = response {
                    print(response)
                } else if let error = error {
                    print(error)
                }
            }
            .progress { progressData in
                print(progressData)
        }

Thanks!