htaccess rewrite for language subdomains

I need to point subdomains like es.domain.com to /public/www/index.php
The problem is my host does NOT provide me to set a path, I can only set up the subdomains for “local use”, which creates the folders in the public directory

My structure is

/public/
/public/de/
/public/es/
/public/it/
/public/www/index.php

My host told me to use .htaccess files inside the sub domain folders.

I tried, for example in /public/es/ something like

<IfModule mod_rewrite.c>
    Options +FollowSymlinks
    RewriteEngine On
    RewriteBase /
    RewriteCond %{HTTP_HOST} ^(de|es|it).mydomain.com$
        # Create an environment variable to remember the language:
    RewriteRule (.*) - [QSA,E=LANGUAGE:%1]
        # Now check if the LANGUAGE is empty (= doesn't exist)
    RewriteCond %{ENV:LANGUAGE} !^$
        # If so, create the default language (=es):
    RewriteRule (.*) - [QSA,E=LANGUAGE:es]
        # Change the root folder of the spanish language:
    RewriteCond %{ENV:LANGUAGE} ^es$
        # Change the root folder:
    RewriteRule ^/?$ /public/www/index.php
</IfModule>

But I am getting a 404 on this:
The requested URL /public/www/index.php was not found on this server.

In my DNS list I see that
es.domain.com CNAME onlinux-it.setupdns.net
while
www.domain.com CNAME domain.com

I tried also assigning
es.domain.com CNAME to domain.com
but that did not change anything.