With Ubuntu, you'll need to install support for the file system

sudo apt-get install exfat-fuse exfat-utils

If you're using gdisk to create a disk and add a partition, it will ask you what code you want to use. For an exfat system, that is 0700. For a large disk (more than 2TB) you'll also need to use a gpt partition scheme. You can also use parted, as below.

sudo parted /dev/sdd mklabel gpt
sudo parted /dev/sdd mkpart primary 0700 100%
sudo mkfs.exfat /dev/sdd1