Proper way to run Plex as another user with systemd [Ubuntu Server 16.04 LTS]?

I’m sorry, I don’t think there is an official guide to change user, or I can’t find it! Read a lot of articles, just glad this works now. Sorry if I was wrong.

I basically wanted to mount and use exfat external HDD with Plex.

I tried the fstab method, but the HDD is removable and I remove it often, and replace it with others HDDs as well.
https://support.plex.tv/articles/200288606-mounting-ntfs-drives-on-linux/ didn’t work for me (I thought exfat could work like NTFS), and fails to boot (have to read about fstab)

Then I tried https://support.plex.tv/articles/200288596-linux-permissions-guide/

But exfat doesn’t support permission for users (not Plex fault)

then I tiried Change what user Plex runs as (but that doesn’t work also)

Anyways, it would be great if you could do a write up for exFAT hdds as well. Either fstab permissions have to be changed, or Plex can be made to run as a user in Linux.

Thanks!