For the closed test, you will be using your Steam account to play the game. There is no need to sign in, just get in the game, choose a server, and start your shift! Your name will be automatically set to match your Steam name.
We will do our best to make sure that your account's progress carries over from the Beta Weekend to future releases, but there is a chance that some changes will need to be done as we continue development and take beta feedback into account. Things such as level progression or the order of weapon/attachment unlocks can change, which will result in the need for some changes on your account. However, progressing in the tests will mean that you do not start from scratch in the future