For those asking why isn't opened yet, read the main post:
Current Status: Closed
Hello PBE’ers! We have seen enormous growth of the player base on the PBE over the last few months and we’d like to ensure that we are preserving the experience for those who have been participating in providing bug reports and feedback.
As such, we will be temporarily closing sign-ups. We do plan to re-open them in the future but we have multiple changes we’d like to make before allowing the population to grow further. At this time, we do not anticipate sign-ups opening for approximately two months. Please note, however, that this may change randomly as necessary.