Dear infollec,
You can follow these steps:
1. Please go to PHP.ini file, change display_errors = On to display_errors = Off
2. restart Apache.
3. Then reinstalling the quickstart again.
Or
Please go to installation/index.php find code:
define('_JEXEC', 1);
=>Edit to:
define('_JEXEC', 1);
ini_set('display_errors', 'Off');
Thanks.