Thanks, guys. I didn't get back to this for a week.
I found that there was an error in the folder names after unpacking the files. The sample files all include `Sample_Header.php` (located in the samples folder. This has the lines,
if (is_file(__DIR__ . '/../../Common/src/Common/Autoloader.php')) {
include_once __DIR__ . '/../../Common/src/Common/Autoloader.php';
PhpOffice\Common\Autoloader::register();
} else {
throw new Exception('Can not find the vendor or the common folder!');
}
but the extraction of the install files created `Common-master`. Renaming the higher-level folder to `Common` seems to have resolved the problem.
Hopefully this will help someone else.