Authentication packet error "ion auth"

Hi guys, I would like to create an administrative panel for my small test app to learn with codeigniter, I came across the "Ion Auth" package.
https://github.com/benedmunds/CodeIgniter-Ion-Auth

I followed the simple instructions, which are nothing but unpacking and loading the files into their folders.

But later I went to my site to test it all: mysite.com/auth me by mistakes

PHP Code:

Severity: Warning

Message: is_dir(): open_basedir restriction in effect. File(/var/lib/php/session) is not within the allowed path(s): (/var/www/vhosts/mysite.it/:/tmp/)

Filename: drivers/Session_files_driver.php