If you just go to page 1 everything is very well explained, especially where to find updates (Telegram & Twitter).
Be patient: if you joined the 3rd AD you'll receive your free coins. If you're looking for the 4th: be kind and go read this info yourselves before posting.

In any case, for obtaining the #4th round: there will be a Bounty (to be announced) and a reduced Airdrop (which was announced this evening at 19.00 GMT).