iClusta+で「Intl Extension」を有効化する方法があるのでしょうか？

前提・実現したいこと

レンタルサーバーのiClusta+にて、PHPの設定をPHP7.2にしてEC-CUBE4の新規インストールを行いたいのですが、PHPの「intlライブラリ」がインストールされておらず、システムエラーが発生しています。

発生している問題・エラーメッセージ

[2018-10-15 14:05:48] admin.ERROR [62d582cfc0953fd41535abfbbc190608] [7d71f89] [1] [Eccube\Log\Logger:log:64]
 - システムエラーが発生しました。 
["Attempted to load class \"IntlTimeZone\" from the global namespace.\nDid you forget a \"use\" statement?","/shop/vendor/twig/extensions/lib/Twig/Extensions/Extension/Intl.php",71,
"#0 /shop/src/Eccube/Twig/Extension/IntlExtension.php(72): twig_localized_date_filter(Object(Twig_Environment), Object(DateTime), 'medium', 'short')
\n#1 /shop/var/cache/prod/twig/c6/c61bdd38d0f292b19c4e66925dff5f8f27ab0468f32d3118f13d5af26f7d8cb2.php(117): Eccube\Twig\Extension\IntlExtension->date_min(Object(Twig_Environment), Object(DateTime))
\n#2 /shop/vendor/twig/twig/lib/Twig/Template.php(390): __TwigTemplate_14a5c96cd1171026c4630726aba652508ac6fbc366ba96cf3a63ef49112ac054->doDisplay(Array, Array)
\n#3 shop/vendor/twig/twig/lib/Twig/Template.php(367): Twig_Template->displayWithErrorHandling(Array, Array)
\n#4 shop/var/cache/prod/twig/64/64d1eeda182e849d1baf0c08d4df77239ebade7fbe21cdf498f1e1744d619293.php(31): Twig_Template->display(Array, Array)
\n#5 shop/vendor/twig/twig/lib/Twig/Template.php(390): __TwigTemplate_3eacd0779a977e88e162280994d5619256de137bcbb84f114ff56f1c77ed307f->doDisplay(Array, Array)
\n#6 shop/vendor/twig/twig/lib/Twig/Template.php(367): Twig_Template->displayWithErrorHandling(Array, Array)
\n#7 shop/vendor/twig/twig/lib/Twig/Template.php(375): Twig_Template->display(Array)
\n#8 shop/src/Eccube/Twig/Environment.php(54): Twig_Template->render(Array)
\n#9 shop/vendor/sensio/framework-extra-bundle/EventListener/TemplateListener.php(103): Eccube\Twig\Environment->render('@admin/index.tw...', Array)
\n#10/shop/vendor/symfony/event-dispatcher/EventDispatcher.php(212): Sensio\Bundle\FrameworkExtraBundle\EventListener\TemplateListener->onKernelView(Object(Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent), 'kernel.view', Object(Symfony\Component\EventDispatcher\ContainerAwareEventDispatcher))
\n#11/shop/vendor/symfony/event-dispatcher/EventDispatcher.php(44): Symfony\Component\EventDispatcher\EventDispatcher->doDispatch(Array, 'kernel.view', Object(Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent))
\n#12/shop/vendor/symfony/http-kernel/HttpKernel.php(156): Symfony\Component\EventDispatcher\EventDispatcher->dispatch('kernel.view', Object(Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent))
\n#13/shop/vendor/symfony/http-kernel/HttpKernel.php(68): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
\n#14/shop/vendor/symfony/http-kernel/Kernel.php(200): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
\n#15/shop/index.php(58): Symfony\Component\HttpKernel\Kernel->handle(Object(Symfony\Component\HttpFoundation\Request))