On a Linux system with source-built UE4, how do I add assets (i.e. Animation Starter Pack)?

I am watching a tutorial and it tells me to go to my Library > Vault in order to add this asset / plugin / addon (IDK the right term, but I think it is asset).
However, on my Linux system, installed with these instructions, I do not have a Vault / Library. Instead, all I have is UE4 Editor itself, which is what people get on Windows when they go to Library > My Projects on the UE4 Launcher.
I have tried looking at the Documentation and Google, but I must be using the wrong keywords because I cannot find how to get assets from the Marketplace. One thing I found is a Github page of an Indian dude of the very same asset pack that I want to use, but I do not trust the source because I only found it with 1 commit, posted in 1 forum question with 1 answer (the Github Page). This does not really help me in the long-run because I want to use other asset packs.
I also have tried going to the website > Marketplace > Assets > Animation Starter Pack > Download. But the Download button does not really work because I do not have the UE4 Launcher, but only the UE4 Editor.
Anybody have tips?