You can add members to your plan in two ways:

Home Screen on Desktop:

On the home screen on the desktop dashboard at my.cloaked.com, you can access the quick button to add more users:

Subscription Settings:

On mobile app and on desktop, you can navigate to Settings --> Subscription

Within which you can add more members:

Mobile App

In the Mobile App, you will need to access an webpage outside the app to add users to your subscription. To do navigate there, you will need to open the profile pane at the top left, navigate into Settings, click "Subscription", and select "Manage Subscription"

From there, you will be prompted to open your default browser and log into Cloaked on the web. This page should allow you to manage your family plan as described above.