Not able to download or upload files from File Manager

Error Message

In file manager it says could download

Other Information

When i go to my file manager to download or upload the file it neither download nor upload the file.

When download it gives error could not download / something went wrong (not remembering exactly)

And when uploading the progress bar js completed for uploading but file is not uploaded.

PS: Plz tell any way by which i can connect my FTP account from my smartphone.

You need to use ftp app