I get an 'Itunes Match Required' popup when trying to play music files from CD's on my iPhone, songs files don't upload to iPhone.

I have a mac OSX with Mojave 10.14.6 with a 2019 Macbook Pro (I can't update yet due to software compatibility). I have a 2020 iPhone SE and am attempting to upload a short iTunes playlist to it via iTunes. When I drag the playlist to the iPhone, songs that I made in Logic, or songs that are apparently not labeled properly, upload and play from the iPhone fine. But the other songs don't seem to upload and are greyed out when viewing my iPhone 'On My Device' in iTunes. When I go to the playlist on my iPhone, I see all the songs, but when trying to play the songs in question I get the warning 'Itunes Match Required. This item cannot be downloaded because you are not subscribed to Itunes Match.'

All of the songs in the playlist were legitimately purchased as digital files or the CD's were burned to iTunes. Left clicking on the songs in iTunes and going to Song Info for each song, they all point to their files on my external harddrive. When in iTunes on my computer, they play fine (and I can hear my external hard drive firing up to find them). Why is this happening? It seems like the iPhone is assuming that I don't own the songs, even though I am trying to upload actual files.

It's very frustrating that apparently the apple software and technology for anyone who actually owns their music is regressing and becoming unusable.