[Risolto] Translated language under root URL

Background of the issue:
I am working on a site under development and trying to configure WPML to use the default language, Swedish, under a URL sub-directory (/se/my-page) and a translated language, English, without a sub-directory structure (/my-page).

Symptoms:
No specific issue or error message mentioned.

Questions:
How can I configure WPML to use the default language under a sub-directory and a translated language without a sub-directory?