In previous versions of Wowza, it was possible to call a playlist using a designated/arbitrary filename. In current versions, this is no longer supported. You need to use playlist.m3u8 for your workflow.
m3u8 urls are created dynamically within Wowza and they have a request handler that intercepts the request and directs it to the code that creates the returned content.
It is not possible to have a static file with a .m3u8 extension that points to another .m3u8 url.
As Tim mentioned, you need to call playlist.m3u8 with the stream name that is being published or the vod file name that you want to play. This will return the chunklist_xxxx.m3u8 url which contains the list of media segments.
If you call chunklist.m3u8 without a session id, one will be assigned automatically but the next time it is called from the same player, a new session id will be assigned.
Can you explain why you want to use custom urls? There may be a different way to do what you want to do.