https://wccftech.com/halo-infinite-multiplayer-preview-2-out-on-september-24th-available-to-many-more-players/

The second Halo Infinite multiplayer preview test is scheduled to be available on September 24th, as announced a few hours ago by developer 343 Industries.

It should also be far easier to get in, as all those fans who've registered for a Halo Insider profile before September 13th (next Monday) are eligible to be selected.