Help needed with .htaccess

I have a website which needs to be changed from Nginx to Apache webserver. The index directory is nl.html but the HTML extension is removed from the address bar. If I visit the website example.com it shows in the address bar the following URL: example.com/nl but actually it's nl.html. At the moment I have the following .htaccess

RewriteEngine On
RewriteCond %{REQUEST_URI} \.html$
RewriteRule ^(.*)\.html$ $1 [R=301,L]

When I visit the website the root URL is shown without the /nl. If I visit /nl/blog it shows a 404 but it should show /nl/blog.html the issue also appears on other files. What am I missing here?