Digger Enterprise Edition is available as a SaaS offering. You can try it out for free by signing up at ui.digger.dev. The best quickstart for this is either the self-guided tour on the website or the quickstart pages found here: Since the backend hosted on ui.digger.dev is based on the EE image it will enable you to trial the EE functions. Once you have the basic version of the workflow running you can request a license key by speaking to the team and update it in the digger_workflow.yml step like so: 
      - uses: diggerhq/digger@vLatest
        with:
          digger-spec: ${{ inputs.spec }}
          # ...
          ee: 'true'
        env:
          GITHUB_CONTEXT: ${{ toJson(github) }}
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          DIGGER_LICENSE_KEY: ${{ secrets.DIGGER_LICENSE_KEY }}
The key changes is passing ee: true and the license key as an env variable to the workflow. You can then proceed to perform improvements to the workflow as seen fit.