why am i getting directed to Error 404 page when trying to open website Manager?

404 page does not count toward your page allotment.
Per Google: https://www.google.com/search?num=30&site=webhp&source=hp&q=404+error&oq=404&gs_....
"The HTTP 404 Not Found Error means that the webpage you were trying to reach could not be found on the server. It is a Client-side Error which means that either the page has been removed or moved and the URL was not changed accordingly, or that you typed in the URL incorrectly."
Generally there's no need to make any adjustment. Removing the 404 page may disable your customer to be directed to your site. 404's may be produced by page name changes.

Fixing the Website Builder 404 error
https://community.homestead.com/homestead/topics/fixing-the-website-builder-404-error?utm_source=not...

Hello Fawad8709

Are you referring to Websites Manager in your Homestead account? Or the builder? I just tried going into your websites Manager and did not get any error. You have over 100 sites though, which takes awhile to load. It is possible the connection timed out. I would try a different browser.

You said "Also my website is down" but again you have over 100. Which one are you having trouble with?