In UE4 it’s the UMG that handles screen interface which is composed of multiple widgets interacting with each other. If you’re not familiar with the system, your best bet is to look at at least [the first 3 guides here][1].
While there seems to be quite a bit of [journal / quest tuts available on YT][2], I’m not sure which suits your needs the best since I completed none of them. Do consider scrubbing through a few and see if anything resembles closely what you’re after. edit: seems, you’ve tried that.
On the most fundamental level, you will need 2 widgets. One that represents the journal and another one that represents the quest itself. The basic logic loop would look something like this:
It can actually be as simple as that but can also grow in complexity as UI often does 
Do tell if that helped at all.