Server hook priority?
I was looking through some documentation and it mentioned there was some hook priority attributes, BeforeAfterCompletedFailed, and Canceled. I tried added this to a hook and the compiler threw an error, I'm guessing they arent a thing anymore, is there a way to give a hook for a plugin priority or ensure that hoos is ran last?

Isn't that guide for uMod and not Oxide

There is no priority in Oxide other than the order in which your plugin was loaded. The guides you found are for uMod.