[Malte Müller]

You tried bbcode embeds which don’t work here or in WordPress in general. In posts you can embed audio and video but these are not in the system so you can’t via the link button (A reason more to upload to the site instead, we talked about it ;-)).

You have to use HTML directly:

<audio controls src="https://celluloidtunes.no/non-website/alcoa%20-%20the%20jail%20-%202.mp3" loading="lazy"></audio>

Spaces or any special chars in file names may cause trouble.

For a video replace “audio” with “video” and best set also a width:

<video controls src="https://celluloidtunes.no/somevideo.mp4" loading="lazy" width="700"></video>