you have to have a client that can play the content
output via a HDMI splitter
record the screen from the second computer
you now have a 4k recording
That constitutes a webrip.
A webdl means you need to crack widevine or whatever protections Netflix has in place.
How you crack that means you most likely need a L1 key which is the highest protection and no one is going to tell you how to get one or crack it. If they do they risk making their way & key public and then it will be patched and “everyone” will be worse off.