Local Sign-in
Should you prefer not to use Fitbit or Google sign-in credentials, you can create a new account by clicking the "Sign up using Email" link on the top right of the page.
Once your account is created, just sign-in using this email address and password. Be sure to use a real email address, as it can be used to retrieve forgotten passords, and to receive email alerts.
The options concerning physical activities are not available for users signed in using a local account.