So to access music I already own and loaded onto iPhone, I must now purchase a subscription to Apple Music or iTunes Match??

According to: Turn on Sync Library with Apple Music - Apple Support

"If you don't subscribe to Apple Music

• If you only want to sync your existing music library across all of your devices, and not any music from the Apple Music catalog, you can subscribe to iTunes Match on your computer. iTunes Match lets you access your music library on any Apple device or a PC with iTunes for Windows.
• If you buy music from the iTunes Store, you can redownload your past music purchases on your Apple device or a PC with iTunes for Windows.
• You can also manually sync music from your computer to your iPhone, iPad, or iPod touch."