Difficulty with AddOn installation
 

Reading how to install addons for ESO everyone says to use this path:

C:\Users\< username >\Documents\Elder Scrolls Online\live\

This path doesn't exist for me.

I have ESO through steam and this is the path for me to get to ESO files:

C:\Program Files (x86)\Steam\steamapps\common\Zenimax Online\The Elder Scrolls Online

- there is no "live" file to create an AddOn folder in so I am not sure what to do. Does anyone have any further instruction?

the instruction is more than correct. run the game 1 time and the folder will be created automatically

I have been playing the game non-stop for a week and that path doesn't exist for me.

Addons with Steam
 

I suggest you check this discussion on the Steam forum for ESO:
No addon folder when using steam. In particular, the comment about needing to change the permissions so that ESO can create the directory...

If I remember correctly there is also a C:\ProgramData\Elder Scrolls Online\live

Either way the problem Virus programs I have encountered with guild members and users of LOOT, Wrye Bash, and xEdit are Avast and Kaspersky. Remove those, disable Protected Folders, and see if you can find the folder under My Documents or ProgramData.

Here is described how to find the addon folder:
https://www.esoui.com/forums/showthread.php?t=8858

Best and easiest way to detect the folder, imo: by using the ingame screenshot functionality as described there as well.