Latest news on it: http://www.aq3d.com/news/open-beta-1/

Not sure if they'll be available through play store/istore right away but assuming they'll have the apk available if not.

Anyways didn't see this posted so hopefully those who didn't know are now informed.

EDIT: As of now the OB has started! you can find it on steam via the early access section(should be top of new releases) as for mobile I believe it's up on the app and play stores but haven't checked first hand.