Signing in to the launcher
The launcher signs in through the website in your browser: how to confirm the sign-in and what to do if it fails.
You don't type your password into the launcher: you sign in on the Myrcraft website in your browser, and the launcher never sees your password.
In the launcher, click “Sign in with browser”.
In the browser that opens, sign in to the website if you aren't signed in yet.
Check that it's the right account and click “Allow”.
Go back to the launcher. You can close the browser tab.
If sign-in fails
The browser didn't open — click “Cancel” and try again.
“The sign-in confirmation timed out” — start the sign-in again.
Signed in but can't play — verify your email.
The launcher says “No access” — your account doesn't have access to the game test yet. You can see your access level on the “Game” page of your account.
On Linux the sign-in isn't kept between launches — the launcher needs a system password store (GNOME Keyring or KWallet).