WebScrapping - Website gives different HTML source code than it is

I'm trying to scrap HTML code from this webpage: https://www.hyatt.com/. When I RMB -> View Source, it shows it's HTML code. The problem comes when I'm trying to get HTML of this webpage from my program. It gives a different HTML code.

I've tried scrapping this webpage through WebClient and HttpWebRequest&HttpWebResponse from C# with using credentials and useragents, but I'm still unable to get the right HTML code.

The MAIN problem is that is says it's mainterance, but it is not. I've also found an information that this could be because of https.

I would like to get the right HTML code in a variable, just like when I visit the website through browser -> RMB -> View Source.