Virtualbox refuses to start on macOS High Sierra 10.13.6

I've been having this issue like forever and had to use other products, but now I really need Virtualbox to work for a project of mine.

The error I've been getting has always been the same:

Apertura di una sessione per la Macchina Virtuale Prova non riuscita.

The virtual machine 'Prova' has terminated unexpectedly during startup with exit code 1 (0x1).

Codice di uscita:NS_ERROR_FAILURE (0x80004005)
Componente: MachineWrap
Interfaccia: IMachine {85632c68-b5bb-4316-a900-5eb28d3413df}

I've tried everything I could to get around this, including the complete manual removal of every single file Virtualbox has ever created on this machine and when I re-installed it I still got the same issue.

Specs: macOS High Sierra 10.13.6 Mac Pro 2011