Please note that the username is not necessarily your email address but was set during the registration process. In case you have forgotten your username, you will find it in the confirmation email that you used to confirm your email address.
Please do not save the password in the password manager in your browser. This can lead to login errors and is not recommended for security reasons.
As a registered customer you can save your invoice adress as well as your delivery adresses and with a few clicks you have placed your order - without entering already known information.