I can't download/move songs to SD card

[Hirojack]

I have a Samsung J7 Prime, and i get an error every time i have tried to use the SD card:

• When I'm trying to download the songs directly to the SD, the download stops after some songs showing a connection error, and the option to select the storage disappears whit all the synced music.
• When I try to change the storage after downloading the songs to the internal storage the application shows an error and all the data (including the account session) is deleted.

Even though the internal memory is not small, my library is quite large and I like to save it in a good quality, so it uses a lot of space. I have tried to format the SD, change it and restore device, but I can't solve the problem.