In order to facilitate the sharing of files between the Windows 10 host machine and the Virtual Machine running ISE tools, you are provided with an installation option to specify a shared folder. See the Oracle VirtualBox documentation: 4.3 Shared folders.
The directory that you specify will be available on the virtual machine under /home/ise/<shared folder name>.
For instance, if you specify the Windows 10 host directory c:\xilinx_projects\test_design or all_ise_designs at installation time, its content will be accessible on the ISE Virtual Machine under /home/ise/test_design or all_ise_designs.
The installation process only allows you to specify one shared folder, but it is possible to configure additional shared folders post installation. See Chapter 6, ISE Virtual Machine Configuration for more details.