You can join your Nucleus family using the Home Code provided in your invite email, or provided to you by the family administrator.
If you're the Family admin... you should log into the mobile app with the same email address and password you used to create your Nucleus account. You'll then be prompted to complete your profile and enter your Home code. At that point you'll be connected to your other Nucleus devices.
If you've been invited by the Family admin... You'll have to create an account in the mobile app and then enter the Home code. At that point you'll be connected to the other Nucleus devices in the family.
Please note: mobile devices cannot connect to a Nucleus through a Remote Code.
If you're having issues getting registered or connected in the Nucleus Mobile App, please contact firstname.lastname@example.org.