lightroom – Why do my images look pixelated during/after LR/PS post processing?

I bought the Nikon D810, Lexar card reader and just started using Creative Cloud (LR then PS).

First, when the picture are loading to the GRID of LR for me to choose the pictures to import, the pictures are blurry. Once I choose 1 image for editing it looks perfectly fine while I’m on LR develop mode. I can zoom in and out to work on the details.

Then, I export the image to PS and it looks fine until I zoom in to start working on the details. The image is completely pixelated when I zoom.

I save the picture (from Raw to Jpeg) onto to desktop. I open the folder and see the picture pixelated once I zoom into it.

When I post it onto Facebook it doesn’t look too bad (but not crisp)…

Suggestions and steps into what I need to do. I would Deeply thank you for your instructions. Thanks! sample image attached.. enter image description here