vaanyan_ I'm trying to figure out how to help further, but in the interim, can you try a different device that's on a different network? For example, you could try on your phone while using data rather than your home wifi, or connect a different computer to your phone set as a mobile hotspot (still on data).
When I click the Create an Account button on the site, in a private browser window, I get the EA login page, as in, enter the email and password connected to your existing account. I haven't followed through because my EA account is already connected, so I have no way to test. But I'm not getting an error page. So it appears that this isn't a question of the site overall being down so much as something about your system or connection, or maybe even the region, that's blocking the site.
I don't know any reason Poland would be blocked as a whole; I'm just saying this is what a regional issue can look like sometimes.
In the beginning it showed an EA logging page but that's because before I wasn't logged into EA on the browser pre the sims thing. I've tried it on my phone too on my data plan. This time I used the official polish website
