Haha, just be patient. Keep checking the email that you used to register your Facebook and Steam account. I suggest checking four times each of the three days of October 21st-23rd. As long as you’ve registered, it’ll come if you want. They can’t immediately send out the Keys to every single person instantly at one time.
You can contact support on October 24-25th if you didn’t receive your Beta Key. They’ll most likely need to know your Forum account and also what email you use to log into the home page. Then they can go confirm your email was registered and say sorry or something and send you the beta key.
Also, there’s the fact that they need to 1. Find a Beta Key code for you (They’re doing it through Steam so they need to create Beta Keys through it), 2. Find your email, 3. Send automatic email to you.
The second and third part is easy for them. If you don’t receive your Key until the 23rd or afterwards, blame Steam.