Why can't I walk through between the 2 houses in first person navigation mode?

I am trying to enable 3D walkthroughs for my models without using a game engine, but only 3D software, I created this with Adobe Dimension.
I did not lay down any paths for cameras.
Is there any format that automatically enables walkthroughs without laying down paths for cameras?
Do I really need a game engine to enable walkthroughs?
I would only like to use 3D software to add camera paths, and then navigate it in Sketchfab.
How do I do that?

Perhaps you could use our First Person mode? This will allow you to freely navigate the scene. We do not have collision detection though, so you can walk through walls etc.

Great, now it seems to work.
But “mouse to look around”, how do I do that on a laptop without a mouse?

I wanted to change my angle for the first-person navigation by switching back to orbit, but the angle is reset again when I switch back to first person navigation.
How do I change the angle for first person navigation?

You can use the trackpad for to change view direction.