You should get this once you start the game. If it does not trigger, try closing the game and starting it again or join a match.

When you start the game there is the option on the top of the screen to select a ship and customise it. Chose a ship, fiddle a bit with the few options you have available and wait for the achievement. Try saving your customised ship if that does not work.

When you start the game there is the option on the top of the screen to customise your pirate. Work with the few available options and wait for the achievement. Try saving your customised character should the achievement not trigger.

When you start the game, there is an option on the right side of the screen to invite your friends and form a crew. Your friends need to accept the invite. It is possible that they also need to confirm that they are "ready", it is possible that you need to invite at least two people into your crew (= form a crew of 3 people). It triggered at different points for me and my friends.

You need to find a treasure chest in a battle royal game and open it. You can either play on an "official server" with random people or create a server and play with your friends, both ways work for the achievement to trigger.

Has to be done in Battle royal but works on a private server (if you are the host). Enter salty shore and walk around a bit.

Has to be done in Battle royal but works on a private server (if you are the host). Go to Buccanneer's Bay and walk around a bit.

Has to be done in Battle royal but works on a private server (if you are the host). Go to Huanted Swamps (above the ribcage) and walk around a bit.

This one seems to not always work correctly, you might have to try a few times. You have to be killed by someone, respawn and kill them.
My friend and I got this on a private server in treasure hunt (respawn is a lot shorter than in battle royal). We stood on the same ship and only used melee weapons. It took us a few tries to get this though. It also seems like only the server host can get the achievement.

You have to watch the timing here. The achievement only seems to trigger if you kill someone when your ship is already on fire (shortly before it is desroyed).
My friend and I got this on a private server in battle royal mode: A pulled the plug of B's ship, B reduces A's health to the point where A will die with the next hit. Wait till the ship goes up in flames, then B kills A. B should get the achievement if they are the server host.

Easiest to get in treasure hunt, also works on a private server. Collect treasure chests and hand them in at the outposts. Try no to die or lose your ship (will reduct points). If you have the highest score when the timer runs out you will get this achievement. If you are playing on a private server, only the server host can get this achievement (if they win).

"Claim your first victory upon the seas."

This achievement seem to be broken as of now. If anyone has any tips on how they got it, let me know. I have not been able to figure out specifics for this one.

"You best find some sea turtles, mate."

This achievement seem to be broken as of now. If anyone has any tips on how they got it, let me know. I have not been able to figure out specifics for this one.

"Join two different crews in the same game."

This achievement seem to be broken as of now. If anyone has any tips on how they got it, let me know. I have not been able to figure out specifics for this one.

"Kill 2 pirates with a single cannon shot."

This achievement might be broken as of now. The instructions in the description of the achivement are pretty clear though, it might just be something you have to try a few times.
If anyone has any tips on how they got it, let me know. I have not been able to figure out specifics for this one.

"Now you walk like a duck, so talk like a duck."

It is rumoured that you can get this by equipping two peg legs but I have no idea whether this is true ot not, achievement seems to be broken.