help! install workpress inside rails

I unzip and rename wp-config-sample.php => wp-config.php and conffig it.
it is exactly my file (i have no edit)

// Heroku Postgres settings

if (isset($_ENV["DATABASE_URL"])) {

  $db = parse_url($_ENV["DATABASE_URL"]);

  define("DB_NAME", trim($db["path"],"/"));

  define("DB_USER", $db["user"]);

  define("DB_PASSWORD", $db["pass"]);

  define("DB_HOST", $db["host"]);

} else {

  die("Cannot determine database settings from DATABASE_URL\n");

}

Then I create .htaccess (app/.htaccess) and config(i have no edit):

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /blog/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /blog/index.php [L]
</IfModule>

Then I upload it to blog folder on heroku. And try install but it always return eror 404 (I see logs heroku) my link to install:
https://mywebsite.heroku.com/blog/wp-admin/install.php

ActionController::RoutingError (No route matches “/blog/wp-admin/install.php

Please help me install this.
Thanks so much