It’s not guaranteed that UEFI will work right away, maybe you’ll need to use some custom options to make it work.
As I understand it, this part of guide:
Multibooting Qubes
Would be appropriate for your case if you’ve installed the Kali Linux on separate disk with its own GRUB installed.
But since you’ve installed the Kali on the same disk you should’ve followed this part of the guide:
Multibooting Qubes