I still can't add mp3 files trhough preferences -> local The files -> add source. How do I fix this?
I found out how to get mp3 files onto Spotify without using the old version.
First, you have to download the mp3 file you want to get into Spotify
Next, look into the local files button on the left of the screen, where it should be under a bar called "Your Music"
Then, you can add it to your playlist by using the three small dots, on the left of the song on Spotify, and click "Add to playlist" and add it to your playlist.
THANK YOU, I've had this song on my desktop for sooooo long I just wanted it on my playlist, so thank you for helping me out.