Redirect to localhost after installing Multisite on server

After preparing the site on localhost, I uploaded it on server. Everything works fine by adding both lines to define WP_HOME and WP_SITEURL on wp-config.php and replacing the url site in the database tables. Then I decided to create a multisite network (subdomains) using WordPress Multi-Site Enabler Plugin. An old plugin but worked well with another website created directly online.
In this case, I got a redirection to the localhost/oldlocalwebsite.com/ everytime I try to login.
This is what was added by the plugin in wp-config.php:

define ('MULTISITE', '1');
define ('SUBDOMAIN_INSTALL', '1');
define ('DOMAIN_CURRENT_SITE', 'thenewwebsiteonline.com');
define ('PATH_CURRENT_SITE', '/');
define ('SITE_ID_CURRENT_SITE', 1);
define ('BLOG_ID_CURRENT_SITE', 1);
$base = '/';

and in the .htaccess file:

#Made Multi-Site with Multi-Site Enabler 1.5#
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]

RewriteRule . index.php [L]

By the way I’ve already done this twice manually and I got 500 error.

Any help please ? Thanks.