If you're using a development environment where you don't have Docker available locally (as is the case when using the SAP Business Application Studio), then you can use a GitHub Actions based workflow instead, in the context of your forked repository.
This Developer Keynote repository contains such a workflow, defined in the image-build-and-publish.yml file, and so when you fork the repository you get this workflow along with everything else.
However, for security reasons, GitHub initially sets any existing workflows in a forked repository to a disabled state, so before being able to use the workflow in your own forked repository, you'll see a message like this which will warn you and allow you to enable them:
Make sure you enable the workflows before proceeding.