Download iTunes library WITHOUT access to a PC

I’ve got loads of music in my iTunes library that I can’t access in the Music App on my iPhone or iPad. Everything I’ve read ( a lot) says I need to access iTunes on a PC or Mac 1st to enable sync or Match. But I no longer have access to a PC or Mac. I only have an iPad and iPhone.

How can I get my albums from iTunes library to iPhone without a PC?

thanks, Davo2062