DursunCan in runtime mode, the file doesn't exist on disk, but it can be reached through its URL: https://<your website>/sitemap.xml
If you need to download it to pass it on to a search engine as file instead of URL for some reason, you can access that URL in your browser, then select "save page as..." to download it to your computer.
In runtime mode, you shouldn't place any file at <flarum path on disk>/public/sitemap.xml, as the webserver would like switch to serving that file, and it will never be updated again.
