I can't install the "Grav core" or "Grav + Admin Plugin" ... :(

Sorry guys, but i have this error. When I install to grav, this error:

<?php
/**

• @package Grav.Core
• @copyright Copyright (C) 2014 - 2017 RocketTheme, LLC. All rights reserved.
• @license MIT License; see LICENSE file for details.
  */

namespace Grav;
define('GRAV_PHP_MIN', '5.5.9');

// Ensure vendor libraries exist
$autoload = DIR . '/vendor/autoload.php';
if (!is_file($autoload)) {
die("Please run: <i>bin/grav install</i>");
}

if (PHP_SAPI == 'cli-server') {
if (!isset($_SERVER['PHP_CLI_ROUTER'])) {
die("PHP webserver requires a router to run Grav, please use: <pre>php -S {$_SERVER["SERVER_NAME"]}:{$_SERVER["SERVER_PORT"]} system/router.php</pre>");
}
}

use Grav\Common\Grav;
use RocketTheme\Toolbox\Event\Event;

if (version_compare($ver = PHP_VERSION, $req = GRAV_PHP_MIN, '<')) {
die(sprintf('You are running PHP %s, but Grav needs at least <strong>PHP %s</strong> to run.', $ver, $req));
}

// Register the auto-loader.
$loader = require_once $autoload;

// Set timezone to default, falls back to system if php.ini not set
date_default_timezone_set(@date_default_timezone_get());

// Set internal encoding if mbstring loaded
if (!extension_loaded('mbstring')) {
die("'mbstring' extension is not loaded. This is required for Grav to run correctly");
}
mb_internal_encoding('UTF-8');

// Get the Grav instance
$grav = Grav::instance(
array(
'loader' => $loader
)
);

// Process the page
try {
$grav->process();
} catch (\Exception $e) {
$grav->fireEvent('onFatalException', new Event(array('exception' => $e)));
throw $e;
}

--------------------------------------------------------->>

Probable error for:

php
Requirements
Someone install to grav
php component

Help me, please.

Guys. Please, help me.

I verified someone solutions but, nothing, nothing.

To help, need more information! What is your server for example. It seems that you have php version lower than required (5.5.9). Use code to define the parameters if you don't know them, like this:

<?php

 phpinfo();

?>