How do I get the feedback form script to work in Google Page Creator?
You can’t. As made obvious by the wizard, when you were asked to select the PHP version of the script if your host supports PHP, or the Perl version if your host supports Perl, you need a web host that supports either PHP or Perl (or both). As far as I can tell, Google Page Creator supports neither. Get a commercial web hosting account instead. Incidentally, you may want to read my article on why it’s better to use a true web editor than a site builder.