https://www.pcgamer.com/the-call-of-duty-black-ops-4-open-beta-starts-saturday-unless-you-pre-ordered/

The Call of Duty: Black Ops 4 PC open beta will be available to all Battle.net users starting Saturday, August 11 at 10 am Pacific. Those who pre-ordered or received a beta code from Activision, however, can start playing today—the early beta access period began earlier this morning.

There seems to be a bit of confusion about it, which is fair, because it's not well communicated. While it's nice that you can pre-load, it doesn't help the confusion that anyone can download Black Ops 4 in Battle.net right now even if they can't play it yet.