Your first screen shot shows calibre-plugins which for me using Firefox is a link which when clicked on downloads the calibre-plugins.zip file for me.
I went to the updated workflow run you posted a link to. Browsed down to when calibre-plugins was visible. Hovered on it and it turned blue. Clicked on it and calibre-plugins.zip was downloaded.
Code:
<div>
<a class="text-bold no-underline Link--primary" style="word-break: break-word;" href="/Leseratte10/acsm-calibre-plugin/actions/runs/12741834382/artifacts/2420369752">calibre-plugins</a>
</div>
Edit: attached calibre-plugins.zip from Replace deprecated macos-12 image with macos-13 #226 workflow.