Jul 29, 2019, 06:3707/29/19
Right when you launch the game after installing it. Look at the top right, you'll see a box to click where you're able to connect to your old account with your plarium information.
If you're already in game. Click your portrait in the top right. Under Profile, on the right side you'll see Plarium ID and Facebook logins. Connect to Plarium with your information and you're set.