Does folder exist

You need to unzip the file that you downloaded.

./application/config/autoload.php

PHP Code:

// Load the messages library
$autoload['libraries'] = array(
    'messages'
); 


Yes, I've unzipped both the files, copied & pasted them into application/libraries folder (I also pasted the first one into system/libraries folder) that is leaving the folder names the same - codeigniter-message-library-master & codeigniter-message-master

And I already had existing in ./application/config/autoload.php

PHP Code:

$autoload['libraries'] = array(); 


so I added 'messages' but it made no difference.