Meetings API and Vanity URL

API Endpoint(s) and/or Zoom API Event(s)
/v2/users/xxx/meetings

Description
I got my Vanity URL that shows a page where you can create or access sessions.
However, when I try to create a session via api, start_url and join_url are always generic, not using my vanity url.
Does it have to be set somewhere or should it work automatically?