Hi. I recently published my app on Flathub and have been steadily updating it to make it better.
With it you can download Music from Youtube and tag it to create a beautiful collection of local Music. Check it out: https://flathub.org/apps/net.fhannenheim.musicfetch
On the download done page there is a button on top with a directory icon, which opens the files in a file manager. Can you please try again and click it and tell me where the files have been downloaded to? That may be a mistake on my part