For me, I subscribe to Deezer (or you can do a trial) and run Deemix which is able to download the music in MP3 or FLAC. It directly downloads the music using Deezer’s API.
As far as organizing it goes, I typically just host it with Plex or a Subsonic player like Navidrome.
I know it’s not like this for everyone but I have a 3.5 year old and he is what provides me the energy to keep going and brings me so much joy. Sure, I boot up the Steam Deck about 3-5 hours a week but my multi-hours gaming sessions I don’t miss at all.
For downloading music in bulk, I personally subscribe to Deezer and then run Deemix in Docker which allows me to download offline audio in FLAC. I then serve those FLAC using Plex and Navidrome.