This .htaccess file works with Wordpress installed under a subdirectory wp/ inside the document root.

.htaccess for WP subdirectory installation

# BEGIN WordPress
<IfModule mod_rewrite.c>
    RewriteEngine On
    # Make the admin still accessible from /wp-admin
    RewriteCond %{REQUEST_URI} ^/wp-admin/?(.*)
    RewriteRule .*  wp/wp-admin/$1 [L,R=301]
    RewriteCond %{REQUEST_URI} ^/wp/?$
    RewriteRule .*  wp/wp-admin/ [L,R=301]
    # Base is the URL path of the home directory
    RewriteBase /
    RewriteRule ^$ wp/index.php [L]
    # Skip real files and directories
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    # Otherwise send it to WordPress
    RewriteRule .* wp/index.php [L]
</IfModule>
# END WordPress

Is this the .htaccess file for the root or the subdirectory?

@arin-g It's the main .htaccess file, that completely replaces the one installed by WP.

It works. Thank you!