Accessing Apple Music on iMac through Apple TV

Over many years I have accumulated an extensive music library, some purchased through the Apple Store and some from vinyl records no longer available. It is stored and managed through my iMac (Sequoia 15.1.1). I frequently use Airplay to hear my library through my audio system via Apple TV which is connected to my main AV receiver. This week, when I tried to access a playlist on my iMac, I was stopped by a requirement to log onto an Apple Music account. I have never had an Apple Music account. It would not accept my Apple Account credentials. Now it appears Apple is requiring a new subscription to hear music I have already purchased. Is that true? If not, what am I doing wrong? I've seen several others online with similar issues, and a whole lot of different answers. Anyone know the truth?