Is this a managed VPS? If so, all you most likely have to do is upload mailwizz to a root domain (example.com), a directory (example.com/mailwizz) or a subdomain mailwizz.example.com) of your choosing. During the course of the install, the installation will check to ensure all the necessary PHP modules needed for mailwizz to function are available.
If this is unmanaged, there are plenty of tutorials for installation of Nginx & PHP-FPM (required to execute PHP) on Google and Youtube. Or you can just hire someone.
P.S. Be sure to confirm that your VPS is managed or not first. If you attempt one of the tutorials online and you have a control panel already installed, you'll screw up your server and have a mess to clean up.