How does an admin find out what the linked accounts are for a player? If a player links their discord, how can I look up what the discord name and player name is? This is useful if I ban someone on discord or ingame I would like to ban them on the other one aswell.

Are you asking from a developer perspective or a server owner perspective?

Server owner. It seems like a feature that would be very useful and one of the main purposes of this plugin from a server owner's perspective.

This sounds like something that should be handled automatically. I'll add it to my TODO list. Until then you can open the oxide/data/DiscordCore.json file and search for the steam Id and then copy the DiscordId. To get the user in discord you can simply ping it by doing <@userId> in any chat channel.