Hello,
A white screen like this is usually a sign to a failed connection to game server. However, we first recommend trying these easy steps to try to fix this error:

1) Clear the client cache
2) Flush the DNS Cache
3) Reboot the PC (Modem/Router too if you want to be extra sure)

If this quick fix does not work, then we would recommend either doing a clean reinstall on your client or using a VPN to route yourself around whatever problem is causing the poor connection. Please keep in mind that not all VPNs will work for a given error, and you may need to try a good number of VPNs or VPN servers before you find one that works.
Thanks!