WordPress wp-admin blank after Network install

I just installed a Network on WordPress so that I can use Multisite (path-based). I add the following lines of code to the wp-config.php file:

define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', false);
define('DOMAIN_CURRENT_SITE', 'localhost:80');
define('PATH_CURRENT_SITE', '/mywebsite/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);

and the following to the .htaccess file:

RewriteEngine On
RewriteBase /mywebsite/
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) Users/juan/Sites/mywebsite/$2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ Users/juan/Sites/mywebsite/$2 [L]
RewriteRule . index.php [L]

When I refresh the site (http://localhost:80/mywebsite/wp-admin/), expecting the “My Sites”/”Network Admin” menu options to appear in my wordpress dashboard, I get a blank page.

I checked that the WordPress and the Site Address are: http://localhost:80/mywebsite
I also checked that my Site URL on the wp-options file is the same.

I have no idea what am I missing. Thanks in advance for your help