macbook – The touch bar does not show up but I need F8

I run a Windows virtual machine via an external hard drive. However, when I primer it, I receive the error message. Winload.efi is corrupt or missing but it says I have to press F8 to change some settings so that it works. There is a problem here, I use a Mac Book Pro with a touch bar, so the touch bar does not show up because it is not needed when starting Windows. I have to press F8 otherwise I can not repair the PC. Ideas?

The keypad and display switch control buttons (fn + f7, fn + f8) do not work (Asus ZenBook Pro 15, Ubuntu18.04)

Have Asus ZenBook Pro 15 (UX550GD) and install Ubuntu 18.04. Everything is fine except the two function buttons (fn + f7, fn + f8). Other combinations of function buttons work.