Cant synchronize local songs on my PC (Windows) with my iPhone

[olafkei2]

Plan

Premium

Country

the Netherlands

Device

iPhone X

Operating System

Windows 10 & iOS 12.4.1

My Question or Issue

I dont understand what I'm doing wrong. I read all the forms and followed all the steps. I added my local songs to a playlist, enabled download on both my PC and iPhone but it still doesn't work. The songs just dont download so I can't listen to them on my phone. I tried uninstalling en installing Spotify on both my PC and phone but that had no effect. I even tried it via hotspot directly between my PC and phone (so the WiFi isn't the issue).

Does anyone else have this problem or does anyone know the solution? 

Thanks in advance.