Local Files Won't Sync

[cachoww]

I've been having trouble syncing my local files from my computer (Lenovo ideapad 320) onto my phone (iPhone SE)

I followed the instructions spotify gives me (attached), connecting to the same WiFi network and activating download on both my computer and my phone, but unlike the given instructions, my songs don't "magically appear on my iPhone".

I've been able to sync my songs in the past, but when I got a new computer they all disappeared and I can't get them back onto my phone.

Thanks