Hi Herindi,
I was having some issues with the USB playing on my 2016 Santa Fe; hopefully some of the following notes will help you.
(1) The memory stick must be formatted as FAT32, not NTFS.
(2) I always create album folders (e.g. 'Fat Of The Land', 'Experience', and 'Music For The Jilted Generation' would all be separate folders for a Prodigy fan).
(3) I have only tried up to 16GB in the car - larger USB memory sticks may have problems, and may also be problematic formatting as FAT32. Start with a small one if in doubt.
(4) Files must be in the MP3 or WMA formats - OGG, M4A, etc will not work.
Hope this helps.