No. If the organiser allows it, you can enter without an account. In the first step you then give your first name, surname and country; an email address is optional.
With an email address you get:
- a confirmation of your entry,
- a message when you move up from the waiting list,
- a personal link that lets you withdraw on your own.
Without an address your entry counts immediately, but you receive none of these messages. To withdraw or change it you then contact the organiser, whose details are on the competition page.
Having an account is more convenient: create one and your details are already filled in, you see all your entries in one place, and you can change them yourself.