How can I rename a removable SD card, or create a folder on it. Permission Denied
It sounds like you formatted the card using your computer, or another device. It seems like now your Android device doesn't have proper permissions to write to the card. You can fix this by formatting the card. If you don't want to format the card, just run this on Ubuntu or another linux based system:

sudo chmod -r o+w /path/to/sdcard


This will recursively give everyone permission to write to the card. If the card is empty, you probably just need to apply this to the root directory, with no recursion:

sudo chmod o+w /sdcard/root