Hello, this typically occurs if you have an improper connection to the game's servers, or if the client fails to load. I suggest clearing client cache, flushing DNS cache, then restarting your PC/router. If you still experience issues after doing so, I suggest trying to login while using a VPN, which might require using most, if not all, of the available servers within the VPN before you are able to bypass the issue.

The miniclient does not have a built in VPN, you can find VPN options on the internet.