Removing old iTunes DRM from track that will not copy to iPhone

I went digging through my older computer stuff and found my previous MBP, a 2010 running High Sierra. It boots, and it has a CD drive. It also still has the last version of iTunes on it. I've found a couple of burned CDs in my archives (originally burned to play in the car back in the early 2000s) that may include the track in question. So I'm going to copy the track over to that MBP and see if it will authorize the track, at which point I should be able to use the old version of the Ondesoft converter on it. If it won't authorize there either, then I will load up these CDs I've dug up and see 1, if they're still readable, and 2, if so do any of them have this track. If that doesn't give me a useable track, then I'll look into Retroactive.

I'd still really love to know what's keeping me from authorizing this Mac to play this track. The error I got, as posted above, didn't tell me anything about what may be causing it or give me anything I can use to figure it out, not even an error code I can Google. I cannot express in words how much I hate useless error messages.

The most annoying part of all of this is that when I created the new library, Music decided to save it over my old library, even though I created it with a different name and saved it in a completely different location. If you check my history, you can see that I posted another thread last week about my failed TM drive and my attempts to use a very old drive to replace it temporarily. That hasn't succeeded either. But about an hour or two after a reboot, the old TM drive will mount as read-only (unrepairable, and it has too many bad blocks to trust reformatting it), so I can access at least some of the backed-up data. But because my Backblaze backups have continued without a pause, I tried to recover the earlier version of the Music Library from them first, as that would be the most up to date. But their website was giving me fits. So I ended up digging up in TM the last version of the library from before the TM drive failed. It's a week old and missing several playlist additions I've made in the past week, but it's better than trying to recreate the whole thing from scratch or from the most recent previous one kept locally from two years ago. When it rains, it pours, I guess.

Okay, I found a virtual CD drive app with a free trial period and installed it. I had to reboot to run it, and after the reboot, the track won't even authorize to play, much less burn. When I try to authorize Music, I get this error:

I have received this error before when trying to authorize Music.app, but despite the error, the tracks were still authorized. Now this track will not authorize at all.

I'm going to try the Ondesoft app, but I don't know if it can remove DRM if I can't authorize the track.

Update:

I created a new library for the affected track and one other that's still showing as protected. The old version of the Ondesoft converter is so old, it's looking only for iTunes and doesn't recognize Music.app. I downloaded the latest version (now called Ondesoft Apple Music Converter), and tried to use it, but it appears to be tied only to Apple Music, not the local Music library (despite what the web site says). Also, when I read the documentation for the current version to see if it mentioned the Apple Music/Music issue, I saw that it cannot convert a track that will not authorize.

So now my problem has devolved to the issue that I cannot authorize this Mac to play any protected tracks. I have only the two remaining, and one of them was a freebie that means nothing to me, but this one track is a special version of a song I very much like, and I don't want to lose it. I'm going to look through old burned CDs to see if I have one with this track on it that's still readable, but then I still would have to find a working drive to rip it from.

Does anyone know anything about the error I'm getting when trying to authorize?