If the collaborator already has a TripMapper account, you must invite them to collaborate using their TripMapper account email address.

If the collaborator does not already have a TripMapper account, they must sign up for the TripMapper account using the email address you sent the invitation to; otherwise, they will not be able to see the itinerary in their new TripMapper account.

For example, if the collaborator creates a new TripMapper account with an Apple private relay address, that email address will not match the email address you sent the invitation to, so they will not see your itinerary in their TripMapper account. If this is the case, ask the collaborator to provide you with their Apple private relay email address and resend the invite using that Apple private relay email address. The itinerary will then show in their TripMapper account (as the email address now matches 😉!)