Hello, I found this possible sollution here. This may help you out:
The reason for this issue is because there do not has partition on the virtual disk, so we should first create a partion on the virtual disk, then you can select the virtual disk partition to install mac os.
1.Click Install macOS High Sierra —> Quit Install macOS menu item in top left corner to quit mac os installation wizard.
2. Then select Disk Utility in macOS utilities window, click Continue button.
3. Select the virtual disk in Disk Utility left panel, then click Erase button at top bar, it will popup a window. Input the partition name, select partition format Mac OS Extended ( Journaled ) in the format drop down list, click Erase button at bottom of popup window to start creating the partition.
4.When create partition process complete, click Done button to finish it. Then close Disk Utility window to go back to macOS Utilities window. Now you can select Reinstall macOS to install it again, and you can select the virtual disk partition during the installation process now.