I want to listen to songs on Spotify that I have stored on my laptop. Now I can use the Deskopt app on my PC to access the songs I've stored on it. If I now add some of these songs to a playlist in Spotify and download them to my phone, sometimes I can still listen to the songs that I only have from the PC and have not found directly on Spotify on my mobile phone. But somehow that only works sometimes, although I do everything the same.
Is there a trick?
No. You have to either transfer the music from the pc to your mobile phone or just download youtube with a converter to your mobile phone and import the music that you have saved on your mobile phone into the spotify app. That goes somewhere in the settings.