So the first step would be to install XAMPP VM 7.2.16 (PHP 7.2 because most TYPO3 extensions are not ready for PHP 7.3 – March 2019). Switching PHP-versions is not so easy, compared to MAMP-Pro where you have a graphical interface.

The second thing is, that it comes with a pre-installed version of PHP. There are two versions, one is the normal version, that runs on your operating system and a new way of having it in a virtual machine. It is available for Linux, Windows and OSX. Get XAMPP VM and run the installer on OSX XAMPP is open source, so anyway the preferred path to go. I couldn’t solve the problem and changed to XAMPP VM. First of all, if you try MAMP-Pro it will fail on the last step of TYPO3 9.x FIRST_INSTALL with some database problem due to field length in VARCHAR(255) fields and utf8_unicode_ci versus utf8mb4_general_ci.