It's not obvious (to me, anyway) how to use hugo cross-reference links with org-mode format posts. This very short post gives an example of how to do so.
Here's an example for linking to this post:
../https://hdyson.github.io/posts/post-links/
[[{{< ref "/posts/post-links.org" >}}]]The org-mode link syntax needs to be used in addition to the curly braces.
The use of /* ... */ (which you'll only see if you're looking at the source
of this repo on github) to escape Hugo rendering the literal example is from
this post.