Thanks Erel
Excuse me, my problem was the lack of authorizations and trying to solve it I searched, by the X-plore application, the folder /storage/emulated /0/ but I didn't find it.
After the correct authorizations the folder is accessible and the data written in it, according to X-plore, are in the /mnt/sdcard folder.
So /storage/emulated /0/ is an alias for /mnt/sdcard?