Device: BQ Aquaris M4.5

Android version: 5.1

I have tried everything and every guide I found here and in other places but still can't get my Spotify to store the downloaded songs into the SD card. 

The SD card works perfectly, have all kind of other files on it. The camera stores there no problem, mp3 music stores there no problem.

There should be an option now in Spotify where it allows you to choose where you want to store it, but for my phone those options just don't appear.

I have tried all kind of clean reinstallations over and over, tried formatting the SD card, also saw some guides talking about certain folder on Android/Data but it doesn't show neither thru windows or thru File manager apps (seems like the downloaded files go in a hidden folder now?). Also read some guides say that the SD card needs to have more free space for the app to store it there, but it does have more free space (14gb) than the internal memory (9gb). Have also tried with a different SD card with the same results.

So as it stands, If I choose to download my playlists it pretty much renders my phone useless as the internal storage gets filled quickly, is there any way to fix this? or any way for the app to show the storage options?

Thanks