If you get an error 3024 message while creating your account, it means that either an account or a user profile is already using this email address. Try using a different email address to finish creating your account.
https://support.withings.com/hc/en-us/sections/6216069138705-Withings-App-iOS
https://support.withings.com/hc/en-us/sections/200508327-Troubleshooting