How to parse ajax pages on C#

I am trying to parse a page on C#. There is a list of appartments printed by ajax javascript script when you click on button "search". I am trying to send a query by postman and get json. But I get a error 400, but I entered headers and cookies and parameters. Chrome somehow gets a code in console. So it's posiible. How to do it? Or maybe there is a problem with settings in postman? Is it possible that site has a protection from parsing?