I have downloaded from the grav web site and unzipped the archive into the default /var/www/htdocs folder. As far as I can see all files are present as indicated in the docs.
All the system requirements for grav have been met including the use of PHP 7. It is located in /usr/lib/php. However, when attempting to install grav any php page (like index.php) displays the PHP text in the browser and does not execute PHP.
I can run the scripts supplied. In fact i tried to run the bin/gpm install admin but got an error
Class ‘ZipArchive’ not found when attempting to install the Form package.
I know I am missing something somewhere.