I’m also having a similar issue. I’ve downloaded the game on MacBook Pro (2015) running OS Mojave to try it out and haven’t been able to access the ArenaNet website to create an account since yesterday around 6-7pm uk time.
I have tried all the workarounds so far (disable ad blocker, firewall, JavaScript, different browsers, cleared cookies, cache and browser history, devices, WiFi vs 4g, etc) but I can still only see a blank white screen when trying to access the login or register page of ArenaNet. All other websites load with no issues
This should be fixed, sorry for the interruption!