Yes it absolutely fine and excellent that you have chosen to register and support. When your ID has been verified you will receive an email to download the App.
In the App you can sign up for scheduled tasks that fit around your availability or you just need to ensure when you can support that you make sure the ON DUTY toggle is clicked ON, then when you are unavailable for support click the On DUTY toggle to OFF. That way you will never be sent requests for support when you are unavailable.