App Store Issue

I am trying to download twitter to my new iPhone XR. On my screen appears a "Double Click to Install" area but it won't allow me to double click on it. I say area because it looks like it's supposed to slide out from the side of the phone but it doesn't slide out. If I click anywhere else on the screen, it takes me back to the App search page and nothing happens.

Is this a fault or is there something wrong with my phone?