Just choose which country you want and click the button. Pick whichever location is closest to you, or actually closest to where the content or service you are reaching sits -- for most people that is the same thing, but it is not always, and the account works the same regardless of which one you choose.
WireGuard is a modern kernel-level VPN: a few thousand lines of code, one fixed set of modern ciphers, and no negotiation at connect time. It comes up almost instantly and survives moving between Wi-Fi and mobile data without dropping the session.
