Error 10001 - Unable to Connect
This is an error typically found when there is a connection issue on your end specifically.
There are a couple of options to try and resolve this issue, but note this isn't the games problem.
Switch Networks
You can try switching networks, either from Wifi to Mobile Data, or vice versa. You might have a weak signal on either network so switching to a different one usually solves the problem
Use a VPN
Some Internet Service Providers (ISPs) might be blocking access to the games servers. They are based in China, and some have restricted access