Merging My Music with Apple Music

Hello Friends-

I have an enourmous music library. It resides on a shared drive in my house. It is a NAS (network attached storage).

I have Apple Music. Love it as it introduces me to new music.

My goal is :

to have take the playlists I have on my iPhone,

Synch with iTunes on my desktop.

Synch playlists with my shuffle. ( I have to have tunes when I run and cannot handle bulk of a phone)

My libraries will not merge.

Could it be that my Itunes library on the NAS is too big?

Thank you for any guidance.

Nora