How to deploy a grav website?

Hello! i tried to manually transfer the document containing my grav website to a server that already has a website, so when i write in my browser "http://www.firstsite..com/grav" it gives this error :

Error in the line 9 in the index.php , this 9th line contains "namespace Grav;"

Any help is appreciated :)

The PHP version on the server is outdated as it does not support namespaces.

Grav needs PHP 5.5.9 or higher.

Thank you so much :) i completely forgot that point!