How to operate this latch? Night time in new Airbnb and can’t lock door!

[corpuscl]

Does anyone know how to operate this?
There is like a spring at the bottom so the two pieces that swing out can be pushed down or up. There is a little bit of metal sticking out the top of the top one and the bottom of the bottom one but there simply isn’t enough room to push them down so they slot in.
You can also pull up the bolt at the top though don’t think I should.

I opened the door earlier but don’t remember doing anything special in particular to open it!

Picture?

Ah nevermind I see it now.

I have no idea but bumping for you.

Is that the main entrance door in? What's on the outside - a regular keyole?

You'd think hosts would leave instructions for oddities like that.

It looks like you put the entire black thing over the thing on the wall then snap the top bit back, maybe.
Message your host, I wouldn't mind

Many thanks all - especially autumncrow!

I took your advice and had a look on the outside. All was revealed!

So the outside has a round doorknob (not pictured as didn’t think it relevant!) with a keyhole right in the middle of it.
My side has a similar doorknob but with a button, and this button looked like the ones you press - I’m in North America - to lock it.
But this button did nothing!
However - the whole doorknob seemed to be twistable once I pressed it so I pressed and twisted and lo- it locked!
I was able to test this as there is another patio door I could nip out of to check.
Thanks again! Not in a million years would I have figured out this one. It’s also why I didn’t notice that I’d stealthily unlocked it earlier today!

Still have no idea what black latch is for

Hurrah! Sleep tight.