Head-scratching issue trying to get non-Apple Music originated MP3 music album from my MacBookPro to iPhone 16

I have a third-party mp3 music album i want to move from my macbookpro desktop to my iphone 16. i plug my phone in, go to music, press synch, and it says "to synch music from computer to phone turn off cloud music library.' doesn't say WHERE to turn this off, but I went to my phone, turned off 'synch library' under the music tab in settings, and it read the note: 'if you do this, all apple music downloads from your phone will be removed.' This is a ridiculous feature - who wants to do that?? I just want to add this freaking mp3 album, not DELETE everything I have! It's sitting there staring at me on my mac and yet can't go anywhere. what am i missing?