Starting library in Music App from scratch with existing offline music in Music folder on computer - issues

Hi there, wont bore everyone with how I got into this pickle, but i've tried a few things and it causing a lot of issues. I have set up a new itunes libary (and deleted old ones) and its obviously blank with no songs.

I've set the Music Media folder location in the exact place my 9000 songs are

Music/iTunes/ITunes Media

but nothing automatically syncs

Do i need to import those tracks into itunes? As if so i did try that and it made some of the tracks but not all go into a seperate Media folder. So whilst the 9000 songs were in my itunes they then seemed to be living in two places on my machine and some were not located it seemed messy. Also Do the tracks get duplicated in terms of living in Music App aswell as as on a folder on machine?

How can i just cleanly get these 9000 songs into my Itunes/Music library in a way that doesnt duplicate, keeps things in one place and all files located? These songs are from the same machine. So that is not the issue