The first step is to create an account on Protonmail. If you are new to this service, you may need to sign up. Once you have completed the registration process, you should receive an email address. You will need to enter your password, which is a secure way to access your email. Your password is not stored on the servers, so it will be stored locally on your device or browser. Each time you log in, this password will decrypt your mailbox and keep it safe.

See also - https://techarticles.ca/how-can-you-sign-up-for-protonmail/