Why is my imported HDRI so pixellated?

I’m sorry I’m a bit of an amateur with texturing, and I’ve got a couple of questions:

Firstly, How do you recreate the UV input

Secondly, my hdri looks pretty washed out, as you can see in this thread:
https://forums.unrealengine.com/development-discussion/rendering/1520854-hdri-skysphere-looks-washed-out

How do I get the colours back to normal or at least how they’re represented in the texture, in which case I can leave the max resolution at 2048?

I massively appreciate ALL your very kind help!