Although @webman is correct, it is also possible that the site is loading some files from another place than their domain, and that ‘another place’ is blocking you.
You could determine for sure by using the Developer Tools (F12 usually) in your browser, selecting the Network tab, then reloading the page. That will show you all of the ‘requests’ for the page, and you can determine if there are requests that are blocked.
But I suspect that the site is broken a bit. I use this site to check theme/plugin usage: https://whatwpthemeisthat.com/ ; there are many similar sites available that you can find via the googles.