Its different for all systems. First place to look would be in your servers control panel. Maybe ask your hosting company. Unless your using a separate service.
Quote: A YouTube handle is a unique and short channel identifier that starts with the "@" symbol and is distinct from the channel name. For example, the YouTube handle for the YouTube Creators channel is @youtubecreators https://support.google.com/youtube/answer/11585688?hl=en&co=GENIE.Platform%3DDesktop. You can use this handle to find and connect with the YouTube Creators channel on YouTube, such as in comments, mentions, and Shorts. You can also use this handle as the new YouTube URL for the channel, making it easier for people to discover the channel outside of YouTube. For example, you can type youtube.com/@youtubecreators in your browser to go directly to the YouTube Creators channel.
What are the steps you're expecting to have happen but don't work? Sounds like this is a new feature to be added request if the old way still also needs to be supported.
Ask your hosting company what the correct path is. If you're using very cheap shared hosting its possible its not available on your server.
Jamroom tries to package widely compatible binaries in the updates but if they don't work for your server you are able to use the servers own versions.