The naming convention for CDK Vagrant boxes has changed. It used to contain the RHEL version in the form of x.y (major.minor), but now it only includes the major version, e.g.:

rhel-cdk-kubernetes-7-33.x86_64.vagrant-hyperv.box

2.3 docs come with the old names. This needs to be fixed for 2.4.

I suggest using attributes for the entire file names because there may yet come additional changes in the name, so it'd be convenient to edit the thing only in 'common_content/attributes.adoc'.