I'm having the exact same problem. when i try to join the official server with this account,
i type in my password and two boxes pop up and it says:

Connection to server is Lost.
Quit reason: Authentication failed.

I too tried resetting my password (twice) with no success however this is the
first version i played, so i cant really say if its just a bug in this version
or overall a problem for me. :/

P.s. I can log in fine after i change my nick so I'm pretty sure its not a connection problem either.

FYI to people who bring this up.

The server caches passwords for performance reasons. If you change your password on the website, you will have to use the old password (assuming you remember it) for a while after (a few hours or so).

If you can't wait, go on Hedgewars chat and ask an admin to clear the server password cache.