If your server uses a different username than what wordpress expects for the site it won’t allow it access without you providing those FTP login credentials every time you need to add, delete or upgrade a plugin.
you can temporarily add the following lines to wp-config.php files to over ride this issue.
//*added ftp login credentials to avoid WordPress asking for FTP details every time I wanted to upgrade a plugin*
define('FTP_HOST', 'ftp.yoursite.com');
define('FTP_USER', 'Your_FTP_Username');
define('FTP_PASS', 'Your_FTP_password');
//*If you can use a SSL connection set this to true*
define('FTP_SSL', true);
