Why can't I install vagrant-berkshelf after installing Chef?

Question

Vagrant

I install vagrant according to this documentation.
After the command, vagrant up gives the following:

Vagrant failed to initialize at a very early stage:

The plugins failed to load properly. The error message given is
shown below.

cannot load such file -- vagrant-berkshelf

I realized that the plugin was missing and ran the command vagrant plugin install vagrant-berkshelf , but he told me that I needed to install Chef

Installing the 'vagrant-berkshelf' plugin. This can take a few minutes...
Installed the plugin 'vagrant-berkshelf (5.1.1)'!
Post install message from the 'vagrant-berkshelf' plugin:

The Vagrant Berkshelf plugin requires Berkshelf from the Chef Development Kit.
You can download the latest version of the Chef Development Kit from:

    https://downloads.chef.io/chef-dk/

Installing Berkshelf via other methods is not officially supported.

Installed, rebooted and after another attempt to install the plugin, it again gives the same error that you need to install Chef .
So for the record: I install on Windows 10