Then I went to install via localhost/cockpit/install and the browser just says “This page isn’t working”.
php_error.log
[26-May-2018 16:16:43 Europe/Berlin] PHP Fatal error: Class ‘MongoDB\Driver\Manager’ not found in /Applications/MAMP/htdocs/cockpit-cms/lib/MongoDB/Client.php on line 83
I had the same issue, but I was using MAMP. I had to make sure the mongodb driver was installed on my MAMP server. If you are still having trouble and that is your issue let me know. I will offer my solution.