Hello. I have this problem.on the app.
Everything i start the app download again the music.
I can't find this music anywhere on my device. So is not downloading anything.

If it's stuck downloading, try tapping the download icon (in your screenshot), wait a minute, restart the app, then try downloading again.

The music is downloaded. Now where the hell is it?

I don't think the tracks are accessible outside of the app on Android. On iOS they are accessible via the Files app. Let me see what can be done..

well download... I thought that actually download to the phone as an MP3.

It does download the files, whether they are MP3, AIFF, WAV etc, however, it downloads to a location that is only accessible by the app. Downloading is way better than streaming from cloud storage but it's not visible at the moment.

We are going to implement a new system that downloads to a shared location where you can see the files.

I have subscribed you to the idea here:
https://www.mixo.dj/roadmap/5910-android-app-change-folder-repository-for-the-sync