Make sure that you have the kali repository defined under
/etc/apt/sources.list
It sounds as if you want to install a metapackage that will bring in
other tools. Possible candidates are kali-linux-default and
kali-linux-everything.
Kali is a Debian bvased system, so the command you want to use to
install packages is apt - run as root.
Open a terminal in the template and issues sudo apt install kali-linux-default - make sure that you have sufficient space in the
root volume before you do this - you can change this from the qube
settings.
I never presume to speak for the Qubes team.
When I comment in the Forum I speak for myself.