If you have an existing Iconik account, you'll be able to login to your account by visiting iconik.io and entering the email associated with your account.
By entering your email or using a third-party to authenticate, you'll be able to view any domains that your account is currently associated with to choose which one to log into.
If you have Two-factor authentication enabled you will need to enter the code that is sent to you via email or from your authenticator app.