The process was surprisingly simple with three steps:
There are step-by-step instructions here https://docs.docker.com/engine/install/centos/
Using the curl method worked fine: https://kubernetes.io/docs/tasks/tools/install-kubectl-linux/
(note: trying the yum method did not work as the repo seems to be gone)
And again, just running the installation script: https://k3d.io/v5.4.4/#installation
and we up and running!