VirtualBox is similar to VMware Workstation Player, and is a hypervisor that's an open source and completely free desktop application from which you can run any virtual machine, once it's installed on the host operating system. VirtualBox can be downloaded from this URL: https://www.virtualbox.org/wiki/Downloads
We will now go ahead and install Kali on VirtualBox. Similar to VMware, we will just execute the downloaded executable, which should lead us to the following screen:

Once we click on Next, the VirtualBox should provide options to customize the different ways to store, but by default, we would be selecting VirtualBox Application ...