exFAT is supported on all firmware except 1.0. If you're on 1.0 and you want exFAT, you will have to update your firmware past 1.0. Usage is pretty straightforward; download the .NRO, slap it in your Switch folder, and run the homebrew. The actual challenge is downloading the firmware update files to use with it since its a firmware installer not downloader. And since those files are considered copyrighted content, they must be obtained outside of this forum. However if you read through the ChoiDujourNX OP very carefully, the creator details several ways to obtain those files.