500 Internal Error during installation

Installing Mautic 3
My PHP version is : 7.2
My MySQL/MariaDB version is: 10.3.27

Installing Errors
I am (delete as applicable): Installing

These errors are showing in the installer : 500 Internal Server Error

These errors are showing in the Mautic log :

[27-Nov-2020 17:11:50 UTC] Symfony\Component\Debug\Exception\ClassNotFoundException: Attempted to load class “SimplifiedXmlDriver” from namespace “Doctrine\ORM\Mapping\Driver”.
Did you forget a “use” statement for another namespace? - in file mautic/var/cache/prod/Container0xj6ape/appProdProjectContainer.php - at line 5887

Your problem

I am trying to install Mautic 3 on my Managed VPS server, and I am receiving error 500.

Steps I have tried to fix the problem :

Checked the file and directories permissions and they are fine.