When I first posted this issue I was told it wasn’t possible to add a custom field to a permalink.
Maybe you should try this plugin: https://github.com/athlan/wordpress-custom-fields-permalink-plugin
Or create a custom post type and rewrite your permalinks with a custom post type instead of a custom advanced field. But from my experience rewriting permalinks messed up the website/theme I was developing, in my opinion it’s best to use WordPress’s structure for permalinks.
