At the top right of the page is the Register button. Pressing the button brings up the registration form. You can do a quick registration via social media or you should fill out the registration form (email, password and account type (Merchant or Individual)). In the next step, depending on the type of account, you will be asked to fill in your personal information. Immediately after, a user confirmation message will be sent to the email you will register. Go to your email, find the "Account Approval" message and follow the instructions. Your account is now active.
The account with the email address already exists on the site. To synchronize with Social Network Login plugin please enter the password to your account on the site.