This is how I understand you need to apply - other members here may clarify where necessary:
1. Your wife needs to apply first being the EU sponsor.
2. Application is via an App on her smartphone - this will guide her through the documents required.
2a. Link to App guidance:
https://www.gov.uk/guidance/using-the-e ... -check-app
3. I believe she can apply for the child at the same time.
4. Your wife receives an application reference.
5. You as the non-EU family member can then apply on the app.
6. App will guide you through what has to be submitted.
7. You need to link your application to your wife's reference number.
8. you will receive emails if/when your application has been successful.
9. You as the non-EU family member will receive a card I believe.