If you’re a system administrator and you’ve been asked to create a WordPress Multisite, you’re in the right place. You simply need to add the following line to the “wp-cofig.php” file right above the “/* That’s all, stop editing! Happy blogging. */” line.
define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', true);
define('DOMAIN_CURRENT_SITE', 'blog.example.com');
define('PATH_CURRENT_SITE', '/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);
And then change your “.htaccess” file in the document root to have the following:
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]
Then hand-over to the web developers. They will see the “network menus” and do their thing.
Read more here “https://www.elegantthemes.com/blog/resources/the-complete-guide-to-creating-a-wordpress-multisite-installation”.