Symfonium Android Auto cannot see local folder?

When I use the Symfonium app on Android Auto, it doesn’t see my local folders. Therefore, I cannot play music files that are stored locally on my phone.

Is this a limitation or a configuration issue?

The Symfonium app on my phone works fine when playing local files:

Library → Files → Local device → Music\Remix → Play

The Library on Android Auto, there is no Files option.

I don’t think it’s a permission issue because other Android music apps can do this without any problems.