You can make this a 2 step process and upload files to hdfs.
Step 1: Download the files from ftp server and store in local . This should help : Transfer files from FTP server to local unix server
Step 2: Once you have the files in local you can use hadoop fs -put to transfer the files to hdfs.
Example. if you file name is temp.csv you can do:
hadoop fs -put temp.csv $hadoop_path