Hi novski,
I hope it is not too late. Have you already figured out how to access the external sd card? Anyway, here is an explanation for that: Before you can access the external sd card, you have to mount it. You can mount it inside the android settings: Go to settings > storage > External SD card: mount.
There should be different possibilities on how to mount it, I think (Unfortunately, my phone does not have a sdcard slot, so I can not tell…).
Once you have mounted the sdcard, it should be accessible in amaze under /storage/sdcard1 , I think.
And if you want to access the external sdcard in your music player, I think there should be a possibility in the music player settings to choose the storage location. Just search there. If the default music player does not have a possibility to play the music from the sdcard, then maybe try another music player.