I’ve been using Deemix for several years, but it’s not maintained anymore and it finally stopped working :<
But the way it worked was you paid for a deezer.com subscription and gave the login arl token to the deemix app. Then the app could download the music files using your account.
Is there anything like that these days?
I can’t confirm, but given the question is several hours old without response;
yt-dlp can use webbrowser cookies to use browser login sessions
--cookies-from-browser firefox, which may be enough