Want to try Windows 11 risk-free? Use Hyper-V to create a virtual machine where you can test the new operating system without losing access to your "real" PC. I've got step-by-step instructions here.

If VirtualBox can't overwrite the machine folder, navigate to the existing path and delete the existing folder or avoid creating the VM folder in the Download location.

Adding new virtual servers is a good time to audit host memory and compute to ensure each virtual machine gets enough of each.