Here’s the thread that helped get me up to speed using Scrivener as a composer for LaTeX. As @AmberV explained there, Pandoc isn’t involved here. The Scrivener template is set up to produce a .tex document which I then pasted into Overleaf to compile to pdf.
As I say, now I use Scrivener as a Markdown editor and have Scrivener call upon Pandoc to compile to any output format I want.