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 ISPs have restricted access to those servers. You can try using a VPN whilst playing the game on whatever network you are using.
This usually happens on Mobile Data providers rather than your home network. There are several free VPNs available to try in the Appstore and Playstore.
If all else fails
If you still cannot connect to the game, you can try reaching out to Customer Services via email, as you cannot access the game to contact though their in-game support channels.
Their email is [email protected]