404 errors in admin panel after wordpress installation

I have just installed WordPress 4.6.1. I keep getting 404 errors when trying to navigate the wordpress backend. I got a 404 when trying to login. I refreshed the page a few times and eventually got the login page and successfully logged in. Every other link does the same thing. I have to refresh up to 15 times before the page loads or the settings are saved.

On the frontend, I get my hosting provider’s sales page instead of my new website. After refreshing many times, my website loads, but the styling doesn’t load or only partially loads. How can I resolve this issue?