With the FTP or SSH, have you checked that the directories are presents.
Have you checked the content.
Does the multisites/ikariam
I notice that you have put the path /
www.javler.it/multisites/ikariam
Is you website is at the root of the disk /
www.javler.it
With the hello.php, I see that the path of
www.javler.it is
/web/htdocs/
www.javler.it/home
Therefore, the path for
www.javler.it/multisites/ikariam
should be /web/htdocs/
www.javler.it/home/multisites/ikariam
YES this is a permission problem.
Check also the permission to see if you can execute the files.
For example perform a chmod 777 on the file hello.php and check also that the directory has a chmod 777.
You can also try to create any directory an put the hello.txt and hello.php file to check if you are able to execute the PHP.
Perhaps the owner of the file and group does not match the one that is used by apache and that reject the execution of the script.