How do I add pre-set objects to a project?

So, I downloaded unreal engine and wanted to get my hands on some creative project. I downloaded this house designer thing and added it to an empty 3rd-person project. Then I open it and it looks just like it used to look before ‘adding’ the environment. No furniture to be seen to modify, just some gray stairs and a little robot-like figure. And some endless controls and settings none of which makes any sense to me.
I expected all the objects available from the template to be listed on the side so I can choose from them, then position and customize. What it’s point otherwise? Yet there are nowhere to be seen. I click again ‘add to project’ in the launcher and it says files are already added, do i wanna overwrite.
How do I get them to show up then, how does this thing even work?!? Why isn’t there a basic or beginner control mode?

Have a look for the levels:

How do I get to that screen I don’t see any ‘filters’ menu? Maybe you have some other version, I have the most recent one? I found a level option in the window pane

but I don’t have these option that you show, all that’s there is this:

It’s in the content browser. You always get map/level demos with content.

I found where that is but nothing there:

Look at what folder you’re in

You need to be at the top.