If I want to log in to an existing Campercontact account with Google/Apple, do those email addresses have to be the same?

Yes, to link you to your existing account, the system looks at your email address. Please ensure that you have ticked 'Share my email address with Campercontact' when logging in to Apple. If you use a different address, we will create a new user. Any settings, purchases, favourites, etc. will then not be available in the app.