There are a few things you can do to get some music into your playlist

• Add your MP3 collection to Deezer 

• Contact the artist via their social media channels and request for the tracks/albums to be added to Deezer

As @archaic_email mentioned, you can upload your MP3 music to Deezer.

I’ve check the other streaming services, but no one has the Superman Doomsday album. So yes, contacting the artist is the right next step.