Hi not sure why you are trying to install it on a virtual machine using xampp, if you want to setup on windows you could use laragon https://laragon.org/
It will install a local webserver, and create a local url to play around with Gibbon
If you want to run it on linux, just setup linux as a webserver How To Install Linux, Apache, MySQL, PHP (LAMP) Stack on Ubuntu | DigitalOcean then use this guide How to install gibbon for noobs (like me) on debian 12 or Ubuntu and similar
The other method is much easier, and no need for the VM