Issue with default template after adding languages

I am trying to add multiple languages to my site - I have followed these guides Introduction | Kirby CMS but am currently getting this error

“The default template does not exist”

/en has been appended to the url

site/languages/en.php

<?php

return [
  'code' => 'en',
  'default' => true,
  'direction' => 'ltr',
  'locale' => 'en_US',
  'name' => 'English',
  'url' => '/'
];

Hoping for any kind of direction on how to resolve this :pleading_face:

How did you add the language, via the Panel or manually? It’s best to do it via the Panel, because then the content files are renamed with the language extension, e.g. project.en.txt` automatically. Otherwise you have to do that manually.

Does the default.php template exist in /site/templates/