Level 88
Well this is a PHP7 issue. Once you install PHP7.1, it's not active automatically. You need to do some adjustments on your server or locally to make this work for you.
In the URL I see you use lampp locally. Make sure that lamp[ is using PHP7 here! Maybe this helps: https://stackoverflow.com/questions/34296466/upgrading-xampp-to-run-php-7